I am looking at getting a 6'6" medium action St Croix Premier with a fast tip spinning rod and putting a Pflueger President 6935X on it for large and smallmouth bass. Is this a good combonation?

Sounds like a good combination. You could probably back down to the 30 size reel though. 

I believe a 30 or smaller size reel really, unless you prefer a bigger spinning reel, if so, I'd say your good...

I like the 30 size reel for bass but that is just me I guess.  I think it will be a good combo. But it were me, I would save up a few more bucks and get the avid.

People rave about the President, sounds like it's the best spinning reel under 80. You can't go wrong with either.