Hi I was thinking about upgrading my current tanks. Currently I have two 10 gallon and one 30 gallon.

I was comparing between 75gal 48x18x20 $103. 90gal 48x18x24 cost $167

Which one do you think will be better for goldfish and my pocket?

--AND does anyone have any suggestions for decorating a new bare bottom tank?- -

Well the 90 gal I think is your best bet, but your going to need three filters on that system. I would go with two canisters and one Hang on the back filter.

Decorating barebottom tanks arent hard. I would use a couple of River rocks on the bottom and then get Some Terracottas and place plants in those

I'd recommend a nice peice of driftwood to go in a bare-bottom tank. Those beneficial bugs need somewhere to live!
B)

Thanks for the comments!