In reply to Heike:
I live just up the road from Arco so I might be biased, and I have only climbed at Finale once (but visited various times), but between the two I would say Arco was much better for your group makeup.
Personally I always found Liguria crowded and claustrophobic, while Arco is reasonably relaxed, with plenty of "normal" things to enjoy apart from rock climbing.
Easter is also fine - better than summer!
There are dozens and dozens of sport crags and hundreds of multi-pitch routes (as long as you like). True though, there is not such an abundance of "easy climbing" and so at the most popular crags these become polished. Massone is probably the worst example of this (San Sirio, too).
Good places that spring to mind: La Gola (Arcadialanda sector in particular), Baone (slabs), Muro dell Asino, La Cosina (small), Rupe Secca Sud, S. Paolo, Marmitte dei Giganti, the boulders below Colodri already mentioned (some bouldering and other small crags in this area too).
And loads more that don't spring to mind.
There are also my little crags around our village, but hardly worth driving up for.
The California Pizzeria below Cima Colodri is the climbers nosh stop, and the Conti D'arco bar in the main squre of Arco town is a popular climber place.
However, bear in mind that the further you go up the valley away from Lake Garda (beyond Sarca village) the nicer the valley gets and the cheaper the food is (and camping).