Consistency/ Thresholds

Today was another long run, 12miles and it was the easiest one yet. Since I've been going out w/ a running group, I've been much more consistent w/ weekly long runs and I think it's paying off. I have to admit a lot of doubts about my ability to run a full marathon when I'm feeling wiped out after 10miles but things are getting better. I've tried to maintain a mindset that I just needed to keep doing longer runs and I will adapt; much like a few years ago when my normal run was 3-5miles and an 8mile run would've killed me. I'm still relatively young when it comes to running, having only been doing it w/ any consistency for the last 3years so hopefully this is just part of the extended base mileage build up and adaptation phase. I have toned down my marathon expectations, shooting for 3hr 3omin instead of a solid 3hrs and in all honestly, I'll be ok w/ any finish under 4hrs.
The bad news I've really slacked off my swimming and really need to get back in the pool. Seeing as I only just learned how to swim a few months I ago, I'm betting I should be practicing that much more.
I'm really on the look out for a road bike. There are so few options for off-road tri's and road cycling is much easier to get in quick workouts around and right outside of town.