Will weight lifting help you in the bedroom? Oh yeah!
I think it's pretty obvious that a muscular bod is going to be much more appealing to the great majority of females. But weight lifting has much, much power in the bedroom than simple sex appeal: it's a performance booster extraordinaire as I'll outline below
Lest you think I'm exagerrating, here are five ways that weight lifting should greatly enhance your sex life:
1. Testosterone. We have already covered how weight lifting can boost baseline testosterone long term in our link on Testosterone and Weights. One of the most well-known studies showed increases in LH, FSH and testosterone in strength trained athletes over a two-year period. 
2. Testosterone to Cortisol Ratio. Senior males had significant positive improvements in total testosterone and their testosterone/cortisol ratios from weight lifting.  Obviously, this ratio along with testosterone to estrogen are, arguably, the two key hormonal ratios that men need to control and improve in most cases. This was verified (in the short term) in another study where T increased significantly but C remained relatively the same. 
3. Improves Endurance. One study of seniors found that weight lifting improved walking endurance.  This is the kind of result that has been found by many athletes: strength helps athletic performance in many ways. And let's face it: what you are often doing in the bedroom is downright athletic, O Weekend Warrior! In other words, weight lifting can help you go that extra mile without collapsing on the floor just before the big event.
4) Erectile Dysfunction Markers. Strength training has been shown to reduce almost all of the major risk factors for erectile dysfunction. Its powers are almost magical. One study noted that it improved the following E.D. markers: "a) normalises blood pressure in those with high normal values; b) reduces insulin resistance; c) decreases both total and intra-abdominal [visceral] fat; d) increases resting metabolic rate in older men; e) prevents the loss of BMD with age."  Still other studies have showed dramatic improvements in arterial inflammation. 
5) Weight Management. Forget the idea that men like big "hunks." That may be true for a few women, but research shows that men think that women like a "bigger" man than they really do.  That means most of us guys need to manage and even lose a little weight, especially as we age. Of course, any and all exercise will help us lose weight, but weight lifting has special powers: it ramps up your metabolism for literally days afterwards.
6) New Sex Positions. Need some spice in your love life? Well, weight lifting can open up a whole new world for you. Imagine being able to actually lift your women without passing out or falling backward. That will get her to take notice. Here are some ideas: 10 Sex Positions That Burn Serious Calories. Now don't hurt yourself of course, but the point is that even if you don't do one of these more exotic position, you are going to be able to do a lot more than you could before.
1) Journal of Applied Physiology, Dec 1988, 65(6):2406-2412, "Neuromuscular and hormonal adaptations in athletes to strength training in two years"
2) Sports Medicine, Oct 2000, 30(4):249-268(20), "Strength Training in the Elderly: Effects on Risk Factors for Age-Related Diseases"
3) Journal of Abnormal Psychology, Feb 1985, 94(1):102-105, "Sex differences in perceptions of desirable body shape"
4) Journal of the American College of Cardiology, Sep 2003, 42(5):861 868, "Anti-inflammatory effects of exercise training in the skeletal muscle of patients with chronic heart failure"
5) Acta Physiologica Scandinavica, Feb 1994, 150(2):211-219, "Serum hormones and strength development during strength training in middle-aged and elderly males and females"
6) Annals of Internal Medicine, Mar 1996, 124(6):568-572, "Weight Training Improves Walking Endurance in Healthy Elderly Persons"
7) Journal of Applied Physiology, January 1997, 82(1):49-54, "Testosterone and cortisol in relationship to dietary nutrients and resistance exercise"