I love undies, love them love them love them - the fancier, frillier, sexier, the better. To me there is nothing more powerful than being in a boring suit knowing I have neon green frilly underwear and matching bra on

And now? LOL - I think I still wear some of my maternity undies
I like the seamless stretchy kind.. gosh don't know what the material is but it's not the 'cottony' feeling stuff. I'll have to look - anyway, this are great and can go up (and down) with the weight quite a bit. I too need to get new ones but I'm just not going to do it yet until I'm tucking them too I guess (great visual btw).
There's another brand I love - and try them once you get to goal, and they're called "hanky panky panties" - they come in boy shorts, and thongs - and I know thongs aren't for everyone, but they don't have lines, and these things are gods gift to thongs! They don't roll, ride up, nothing

I don't were them
currently as it would be akin to a sausage wearing a rubber band, but I've saved them all!!
Target is really good for undies - I boycotted WalSnot long ago.