Hey there, Pinjata!
I can feel for you - absolutely. Especially with the "approaching new tables"-phobia. Got the same. After gaming with wonderful bunch of people for some years I wanted to widen my circle of players and the newbies were a catastrophe.
However, then I remembered our first games and told myself I should give them time...and the same lessons I received/I gave my players. I did and they were still something to behold...
I'll just pick the part that caught my interest the most:
The "4 optimizers meet at a table and kick ass" would bore me to death . And when I thought about the things that you wrote you want at table - my players regularly go shopping for clothes, have fancy dinners just because they were too long in wilderness, and always catch me unprepared by thinking about something I didn't think about... (e.g. "an astronomer? that sounds swell, how does he look like? and will he prepare me a horoscope...?").
My suggestions would be:
- communicate it to the group. Maybe they think you're completely content - they are not mind-readers. Or they shouldn't be. Maybe they would like to give something a try.
- switch to a system you never played (and they don't know), asking them to do just 3 games and then it's back to usual bussiness if they don't like it.
- propose that everyone switches to something they always wanted to play for 3 game sessions (e.g. CoC? Shadowrun?).
- use the advice from daremetodareyo - let's say they encounter a reddish dragon (not red...). It's not your standard issue fire-breather...
- try out diceless system or one that is more focused on roleplay.
If this were Shadowrun, I would say "go read Blackjack's guide to bitter gamemastering". Especially the part about downtime. However... go read it . There is lot of good advice.
Other than that - I wish you luck.