Married to a carpenter/construction supervisor here. I don't see anyone else stating this so here goes. Maybe it's just too obvious or too corny but this is what we've done.
After several years of discussing finishing the basement walls, I was getting no where. He just refused. And twenty years later, I'd have to say he was right. He's spent too much of his career gutting, troubleshooting and working in non-ideal finished basements. He insisted that our basement walls stay bare and have clear access. Not only does water try to seep in from the outside and you have to constantly be aware of the humidity buildup while guessing on the amount of damage, if your basement is like ours, the heavy hitters - plumbing, heating/air and electrical - are all routing through there. They were never meant to be enclosed.
The reason he insists that they stay exposed is because he does a constant monitoring of all these things and has saved us alot of money over the years by catching things early. Also, about once a year, invariably, either the washing machine, toilet or kitchen sink develop an overflow or leak problem and we have water in the basement or need to haul equipment down there to clear pipes.
He says that since the earth is warm just a short distance under the surface, most of the surface areas of the basement walls (which are essentially big hunks of rock/concrete) hold their own temperature. Heat is not being transferred out. And in the summer we gain some cooling because they hold the earth's coolness longer than the upper floors of the house.
Our compromise is that he agreed to install thin sheets of 4 ft x 8 ft particle board on the ceiling with screws. That way he can take down an individual sheet and follow a plumbing line without damaging anything I want to look nice. I painted the walls (which are hand poured, very rough, uneven concrete) and some areas of the floor for my workroom. He agreed on carpet in the biggest areas we use for an extra tv area/guest room. The carpet just lays directly on the concrete floor so it can easily be flipped back and allowed to air dry if we notice any dampness or water leaks.
People are always commenting that they think it looks cool down there. I guess it's a bit "industrial" decor looking but it's nice and functional. And the contractors who have had to come out (installing a new heat/air system, a plumbing line tied in for an additional 1/2 bath, etc) immediately smile and comment on the open access to where they need to work. I believe they cut us a bit of slack in their billing because they have a straight shot to get in and out of the space they need to work in without having to be careful. No one talks about that in their per hour rates. But, I know the contractors talk about it amongst themselves, sharing stories of unbelievable challenges getting to the functional equipment in a home -working all scrunched up on their knees with their elbows held in tight, and incurring the wrath of the homeowners for mud on the new carpet or a ding in the corner of the sheetrock as they tried to turn the corner with their ladders and such. They HATE working in these circumstances, as you probably would if you were in their shoes!
Only other mustachians would appreciate this discussion!