Ok, here is some more info. I have been riding for about 5 years, mostly recreationally here in the SW. I have done a several races over the last 3 years and am now in "Sport" class. I am not a threat to the podium, but generally am close, if not in, the top 10-12 riders out of a 25-30 person field. My training right now consists mostly of just riding around the local trails, and some road work (15-30 miles). I have recently started a gym workout, but it is not much to speak of at this point and is not intended for bulking up, but rather toning. I average 2-4 rides/week for about 2hrs/ride and 12-15 miles, depending on the schedule (more miles if on road bike, but same time). Here in the SW we have lots of loose sand and good size rocks, which makes climbing pretty challenging and technical. Physiche-wise I could stand to lose about 10-15 lbs, but my body-type is sort of "mini-clyde" at 170 lbs.
I guess my question is more about the type of terrain I should focus on. Would it be more beneficial to use the road bike or mtb and look for long climbs, more interval training, or something different altogether? As you can tell, I am pretty ignorant when it comes to training strategies. This is the first time I have seriously considered a true "training regimen" outside of just logging miles. If there are some specific questions that would help answer the question, let me know.
I will check out the books.