Garda and Bardolino are probably the best villages for what you're after.
They aren't too far to travel from Verona airport, have lovely walks along the water's edge and flat enough for walking. Lovely squares and restaurants, lots of families and the boats seem to have a good timetable to most places on the lake from both of these and the bus is handy along that stretch of the lake. You could also walk between Garda, Bardolino etc. Great for a first time visit.
Further north is a bit quieter, Malcesine has beautiful cobbled streets, but very hilly. Definitely worth a visit though, also access to Monte Baldo is from here.
Riva is quite a big town at the northern tip, but it is windier up there (lots of wind surfing etc) and definitely had an older clientele overall. It also took a lot longer on the boat to visit the other towns and also to get there from the airport.
The left side of the lake is very quiet- lovely if you are after a secluded villa but a car would definitely be needed, and there isn't much happening.
Densenzano, is where the young, rich and beautiful come to party from Milan arriving in their sports cars at the weekend. I enjoyed staying there well enough, but preferred other villages more. It is handy for the train station with good links to other places.
Sirmione at the bottom is a walled village, I stayed there once and it was lovely but found it very hot without the breeze due to the walls, and the narrow streets got crowded.