more the merrier chief, initially you could get away with 60/90w , but as you go along and ure girls grows you'd really wanna be getting as much light around your bud sites as poss….
If you plan on using the smaller cfls bulbs just add as you go along, if you using a 150w and upwards size(ya know the long one) you are only going to have one focal point of light so bigger watts in this case would provide more penetration…
also make sure you mix your spectrum a bit if you can… 3:1 2700K/6400K for flowering…..
good luck ….