Does anyone know how to tell whether a bench is solid and durable enough? I want to get one, but I've got this worry that the bench will snap.
In my experience they tend to be pretty sturdy. It doesn't really take a whole lot of strength to handle the sorts of weights that you're likely to be working with. Probably the best thing would be to look at the specs, but I don't believe there's much variation between types. Even the ones in the club tend not to vary much from the ones at home.
generally speaking the weight is going to be very close to one set of legs at pretty much all times.
The bigger concern is going to be having a spotter. If you're working out at home without a spotter then you shouldn't need to worry about the bench too much.