I'd second or third something like what thecook suggests as the most versatile: a skinny no-wax ski without metal edges. Find a comfortable classic or combi race boot or touring boot that fits race bindings and buy the matching Salomon Profil Equipe or NNN race bindings. There are closeouts going on at REI now and many ski shops, if you live near one.

Getting a good fitting ski for your weight is unfortunately a hit and miss proposition, even at good ski shops, but with a good classic ski, you'll both excellent grip and glide. My no-wax skis are long (200 cm for my 150-160 lbs) straight sided 50 mm wide Peltonens that a friend gave a me a good deal on ($25 new old stock) that I mounted some race bindings on, and they are pretty darn good. I use them with my classic race boots (no support above the ankle), and classic race poles with normal wide-webbing loop straps. They're not as fast as my race skis, but I'm usually cruising 2x or 3x faster than people with telemark gear. Yes, you can go downhill in them and it is usually fun, especially in a few inches of powder on top of a good base. This type of ski is great for rolling terrain and easy to moderate up and downhills. They won't be up to steep downhills (but an occassional steep hill can be managed with kick turns), but most routes that are trails in the summer are perfect.

I also have about 10 pair of race skis, both classic and skate, and use them in the backcountry depending on location and snow conditions.

I have one pair of metal edged skis: Madshus Pellestovas, with SNS-BC (Salomon Nordic System - Backcountry, currently called Salomon XA-Adventure) bindings matched with Salomon Greenland boots. It's good backcountry gear that the ski author Steve Barnett favored as a light telemark setup, but I haven't used it in years because my original boots were a bit small, and then I broke the replacements by accident(long story...).

Learning some basic classic and skating technique on groomed trails will make you much more proficient in moving around in the backcountry.