I include weight training in my workouts twice a week. Eventually I'd like to go three times a week, but can only fit in twice right now. But it only takes about 45 minutes, and that includes exercises for both upper and lower body. I wrap the weight training around my spinning classes--doing lower body first, then as much upper body as I have time for before spinning class starts, then finish upper body afterwards. This way, my legs get a little bit of a break before the spinning, and I can make the most of my trips to the gym.

Maybe your trainer can suggest some ways to decrease the time you're spending on weights.