I wish I had some advice for you. I just got lucky right at the start of my riding life, and found some shorts very quickly that have worked for me.

My first pair was a cheap pair of gel shorts from Performance, and those DID NOT work. The gel just put a lot of pressure on my undercarriage. Then, I got two pairs of Pearl Izumi, and they have been my shorts ever since. Literally. They only have a "foam" chamois (or whatever it is)...but they have just lasted and lasted and lasted. It is just now time for me to buy some more.

The only thing I mind is, like you, the waistband gets to me here and there on long rides, especially if I have put on a few pounds (duh). I am thinking of trying out the Terry Bella type just for the waistband issue.

Good luck!