So I'm following in the hopes that someone has great advice for either an AT&T phone (so I can keep the same number) and a NOT SPRINT carrier.
Pretty much any carrier unlocked GSM handset will work, but honestly you'll find far cheaper and more flexible AT&T service from one of the five MVNOs mentioned
in the guide than sticking with Go Phone. As for handsets, if you insist on doing a smartphone, look into the Nokia Lumia 635. Dirt cheap even carrier unlocked (get the carrier unlocked model), and has all the important features that most smartphones no longer have: a less insane user interface, good antennas, and a user replaceable battery. There's also no shortage of ultra-cheap, carrier unlocked, used basic feature phones, including Nokia and Samsung candybar and flip phone handsets.
IP, Can you give me some advice?
There's not an easy or simple answer to this for a multitude of reasons, and this risks forking into a whole other discussion from OP. It also highlights the need for researching beyond just the basics sometimes, and questions like this can really show how many rabbit trails you can sometimes wander down when rolling your own given how flexible telecom setup can get at times and how you want to solve the problem. However, you should always know what the technical limitations are first and simply
K.I.S.S. the problem away.
For network coverage, I wouldn't particularly recommend T-Mobile or Sprint coverage in Oregon unless you spend 95% or more of your time in Bend or the areas between Eugene and Portland and never wander off the interstates. Basically, if you spend most of your time in the smaller communities, it won't be worth it. If you stick close to those three major areas, however, and aren't afraid of losing signal on occasion, T-Mo starts to look more appealing....
As for what network Tracfone uses, it depends. They've offered phones for all four major networks. I couldn't really be sure which one is giving you the biggest time of it currently without knowing the phone model number and the first six digits of the SIM card if it has one. It's possible you're just in a bunker with one or two carriers. Most of the Tracfone handsets sold the past few years are usually T-Mobile primary, which does most all of their calls on the 1900MHz bands now, which has poorer building penetration than the 850MHz or lower bands used by most voice services on AT&T, Sprint, Verizon and US Cellular. If that's genuinely the case and you have a T-Mo Tracfone handset, potentially chalk another one against T-Mo coverage for you even if you can use a carrier that offers WiFi calling and it would better explain why you currently have reception issues. However, don't discount
tower placement and distance, either. This means that it's theoretically possible that you simply wouldn't have this reception problem in your home on another mobile network and with a handset that has a decent/better antenna.
If Boonie reception is important, definitely go with an AT&T MVNO and pay for what you need. If it doesn't matter, you can try to take advantage of the whole P'tel WiFi calling thing despite the disadvantages. Any AT&T or T-Mobile handset that supports WiFi calling (including many Nokia Lumia Windows phones such as the 635) should work fine with P'tel's WiFi calling service, and will also provide some of the best experiences as the UMA/IMS calling is baked into the OS now instead of bolted on.
However, if you don't want to go 100% mobile even with UMA/IMS fallback or want to use an AT&T MVNO such as Airvoice, Puretalk USA or H2O Wireless/EasyGo, there's plenty of stand alone VoIP providers in the guide, many of which can do outbound calling only and allow you to set caller ID to an existing number. VOIP.ms paired with a $35 Obihai ATA or a SIPphone app will give you cheap PAYGO home phone/WiFi calling option with a monthly base cost of around $2/month + calls if you want e911 service and an inbound number, it'll give you
all the features you could ever want and more, and it's not difficult to set up
if you just read the instructions. They also have rudimentary SMS support for certain phone numbers, but not for any ported in. If you just want to use VoIP for outbound calling or don't want e911 or the additional bells and whistles, Localphone is a cheaper option.
If setup still intimidates you and you want a more pre-configured VoIP solution that's more traditionally home phone-y, there's either VOIPo or Phone Power. They'll cost you around $7.70-8.33 (respectively) a month when you prepay, but you'll also get 5000 minutes a month to use. Right now, Phone Power is the better deal even if it costs an extra 63¢/month as you'll own the ATA (instead of needing to return it if you cancel/switch), can pay only a year at a time, and have access to all the other nifty features that the Vonage chumps brag about at a third of the price along with all the other truly useful VoIP features you could want. That said, they don't have SMS support like VOIPo does. Unfortunately, that doesn't entirely address the whole SMS-bunker hole issue and integrated service with a single number, either.
Of course, most of the whole SMS thing can be easily made moot no matter home reception if you do embrace getting a smartphone and convince the people who text you to switch to something like XMS or WhatsApp (I dislike recommending the last for a multitude of reasons, but it's owned by Facebook and people love getting their lives strip-mined by Zuckerberg for some reason). Then you're only dependent upon a data connection and you can keep doing the cell phone home phone thing. If that's not an option....
That basically leaves either paying $10/month to Line2 (which supports Windows Phone) or using Google Voice for your main number and needing an Android handset (only for clean Google Voice integration), for better or worse. Still better than Republic, just as easy to set up, and just as reliable for a fraction of the price, especially when either option is coupled with Truphone.
All this said, I suspect your best answer will be found after determining what network your current handset is using. I suspect that if you get someone with a decent AT&T handset (read no iPhones or Samsung handsets) into your new place, they'll probably be fine - but I could be wrong. If that's the case though, you can pretty well roll however you want from that point. If not, it only gets more complex depending on how you want to approach it. Honestly, the easiest is to just use a messaging app and a phone that supports it instead of trying to hybridize, and it only gets more complicated depending on how you want to tackle the problem from there.
To recap, K.I.S.S. You'll notice that the following distilled solutions go from simplest to most complex. Start with seeing if you're using T-Mobile currently and how AT&T coverage works at your new place, then try a Windows smartphone with a messenger app if your family will do it combined with an AT&T MVNO. If that doesn't work, then consider switching to P'tel and UMA/IMS WiFi support on the same handset if you're mostly urban. Lastly if that doesn't work, there's either Line2 or Google Voice maybe combined with Truphone SIM if you don't do a lot of mobile talk time. VoIP service with or without SMS support can be peppered in anywhere else you like along the way, but probably isn't the easiest option overall unless you just want to bring back a home phone.