VTSAX or VTSMX is good and is where a good chunk of your money should be.
Personally, for spice, I like VHT and VDC. VHT is the healthcare ETF. I just look around me and see more people growing to an older age than ever before and all the drugs and healthcare costs that are associated with it. Seems like a no-brainer that this ETF will continue to do well in the future.
I also like VDC, it is the vanguard consumer staples. Invests in things like Soap, Toilet paper, walmart, costco, etc...
REITs are also interesting. I have a very small portion of my portfolio in them...but if you want to "own" some real estate/real estate companies, it's a really easy way.
Just want to reiterate that IMHO, the above "spice" in your portfolio shouldn't ever really be too much more than 10-20%. You're doing good with your VTSMX.