Bookshelf speakers with the best bass...

Unless you are actually putting them on the bookshelf, a good well matched speaker stand will do more to determine how good the bass is, more than anything other variable. So pick a speaker where you like the mids and highs and then carefully choose the stands.

They say Red Rose 1 monitors have nice 'bottom' extension!

I agree with Sugarbrie, great stands like Sound Org. with sand and lead shot, Blue Tac on top will certainly tighten and deepen bass. For $2500 the Reference 3A DeCapos are superb.

I'll second Red Rose. Sugerbrie's advice should also be headed. The Red Rose monitors are ported in the rear, and if they are not set up right they will sound pretty bad. If you are forced to put these into a bookshelf--these probably won't work.