I struggle with opening up my range of hands as well.

I play 6max 50NL and get into the habit of playing too tight. I think I am missing out on some opportunities and need to open up if I want to move up to 100NL. Observant opponents play back at me sometimes and it will be worse at higher stakes.

Have been trying to raise more midsuited connectors and CB on the flop in the right circumstances. Some players do not fold to CB's and you need PopkerAce to identify them.

Like the Op, I think the KT, Q9 hands etc are tougher to play as well. Havent had much luck with them.