Circuit Training Help

[ZenFitness]

Little background:

I'm 35 years old, 6' 2", and 195 lbs. About two to two and a half years ago, I started intensively strength training to put on some muscle, and I ended up injuring shoulder and pulling an abdominal muscle. I gave it some rest and ibuprofen, but it still hurt if I tried to go back to heavy weights after about six weeks. I was laid up from any kind of exercise for about two months and dropped from about 205 to 190 lbs.

About a year ago, I started sprint training, and it felt great. I was mostly doing HIIT on a treadmill or on outdoor runs. I was nervous about getting back to weights, but a friend talked me into trying pushups. Lo and behold, they didn't hurt. Since then, I've double the number of pushups, pullups, and chinups I can do, and I have built a routine around these bodyweight exercises (plus one-armed rows) and running.

Recently, some friends talked me into signing up for a couple of half-marathons this spring, but I recently developed plantar fasciitis from running on some broken shoes for too long and for stepping in a pothole funny in a 15K race. I had a sitdown in head to figure out where I was headed and I realized I was moving down the road to skinny marathon guy. I don't want to be that guy... I also don't want to be the 240 muscleman in the gym, either. I want to stay lean, get strong, and have a high level of cross-trained fitness.

So, I think I'm going to drop the half marathons and cut cardio down to 25 - 45 mins. per session and do a hard run, a swim, and a spin session a week. I also joined a new gym (to gain access to a pool) and had a couple of free sessions with a great trainer. Good news is that levels are great across the board and I'm 8% BF. However, I want to put on about 10 lbs. of muscle and cross train as I explained above. I much prefer that over the run-obsessed crowd I was moving into.

I've also recently found that running really doesn't do anything for leg muscles or lower body. For some reason, I always assumed it would. Oh well!

With the new trainer, we started on circuit training (which I've never done before) focusing on core muscles, kettlebell swings, squats with a kettlebell overhead press, pullups/chinups, and pushups. We have not had time to do the lower body, but we will soon (hopefully). These are free sessions, and, due to $$, I'm wanting to take advantage of them but become self-reliant in the process.

Question: can anyone recommend good circuit training exercises for me for the lower body in particular but also some upper body stuff to mix in?

Also: what resources (books, magazines, etc.) are good in this regard?

Thanks!