Doug, I recently went through the same analysis as you; I was looking for a one rope solution for mountaineering and occasional lead climbing.
I am a beginner with regards to climbing; and civilian equipment is much different than what I used in the military (triple strand nylon rope, steel biners, and swiss seats, for example). Anyway, I settled on the Beal Ice Line, a half rope in 8.1mm at 42 grams/meter. Like you, I don't need more than 30 meters of it since I can't protect more than that (and don't want to run out much!). So, I bought the Ice Line in 70m, and after a little more thought, I'm going to cut it into two 35m sections; one for me, and one for my climbing partner. This will give each of us a 3.3 lb rope more than strong enough for any mountaineering use. Each one takes up only 2 liters and fits in a small stuff sack. Having each person carry a rope is a safety advantage (see ANMA for details). These ropes can be doubled as a twin for leading (no need for the tag/pull line you mentioned), used singly for following/traversing, or they can be connected with a double-fishermans to make one huge 230 foot rope for rappeling down quickly. (Pass the knot via munter on HMS carabiner). If you asked last week, I would have recommended this Ice Line..
However! just this week I discovered the new Metolius Monster dynamic rope in 7.8mm; rated twin and half, at only 38g/m. If I had the chance to make the purchase again, I would get the lighter Metolius. Just make sure all your hardware and technique is compatible with thinner ropes.
Another choice you are probably aware of is the Beal Rando Trail Line, 8mm in 20m, 30m, and 48m lengths. 37g/m for a dynamic twin. But not suitable for bringing up a second in my opinion.