Another thing to try is to use wider tires if at all possible. This reduces the forces acting on the rim/wheel.
If possible I'd go to 36H. The spoke pattern of a 36H will pull together the seam opposite the valve. The 32H doesn't offer that same support - the spokes actually pull the seam apart. I can't prove it helps, but I have a lot of light 28H wheels which lasted a long time (28s pull the seam together too).
Unless you're doing insane miles, carry tons of stuff, or ride through salt water and acid to get to work, you shouldn't be breaking spokes all the time. Either the wheelbuilding isn't 100%, spokes aren't being replaced when necessary, or you need to change some riding habits.
When you break your second spoke in a given wheel, re-lace the entire wheel to "reset" the spoke lifetime countdown. All spokes age at the same time and they'll all break at about the same time. Once a couple goes the rest will follow shortly. Of course you should make sure the spokes are actually breaking. One of my teammates complained of broken spokes - when I examined the wheels, I found the alloy nipples had corroded and were breaking - the spokes were fine.
This is all assuming the wheel was built well and has reasonable and even spoke tension. An over-tensioned wheel is much more likely to break spokes and crack rims (although all spokes will eventually break and all rims will eventually crack/fail). A wheel that is constantly trued due to a bent rim will eventually have some extremely tensioned spokes - those will fail earlier than the normally tensioned spokes. If the wheel is out of true (but ridable) but the spoke tension is even, then leave it alone - the tension used to force the rim into a different shape will contribute towards early spoke failure.
I've rarely built a wheel where the rim is perfect - and the few rims I built recently are horrible (aluminum anyway). If the wheel is built to be as straight as possible, it may not be the strongest. Decide which is more important - form or function - and have the wheelbuilder do things based on your priority. This may result in an imperfect wheel (usually at the seam) but one that lasts a lot longer.
Finally, you're probably putting the wheels under a great deal of stress. Traffic, heavy bags, and a sleepy or exhausted rider isn't good for avoiding holes, bunnyhopping the unavoidable holes and obstacles, and even simply unweighting the saddle as necessary. I understand that you may not have a choice (I've ridden in midtown Manhattan during rush hour - talk about not having too much choice on where to ride) but there are many techniques which will help keep you and your bike alive. They include bunnyhopping (backpacks actually help you to bunnyhop, panniers hurt bunnyhops), slowing/stopping, or being a little firmer in traffic can help save both your wheels and your bike/life/etc. If you're doing 'cross then I'm preaching to the choir but you get my point.
If your wheel problems continue and reliability is more important that lightweight/performance, then I'd look into heavier duty wheels (perhaps a set of wheels for commuting, another for 'cross). Low flange hubs (longer spokes), at least 3 or 4 cross (again, longer spokes), capped with a big, fat tire and tube. Our tandem hits everything hard (we can't bunnyhop it and I've hit some pretty big things on the road) and it's a bit disconcerting to me. However, the wheels (700c 40 spoke with disc brakes) have held up fine over historically rough New England frost heaved and potholed roads, even with a 330 pound "rider" and a 40 pound bike (loaded).
hope this helps,
cdr