How do you decide on distance?

[artifactos]

I need to send in the entry for my first tri (du, really.. I don't have a wetsuit and the water temp will be a bit low) and I'm on the fence regarding which distance to do.

The Sprint is a 5k run, 20k bike, 5k run. I know I could do this, easily. Most of my runs are 4-6 miles (2-3 times a week), I ride 70-100 miles a week, and there is no question in my mind that I could complete the Sprint even in compression shorts without a chamois. I did a brick today of 13 mi bike, 5 mi run, and had plenty of juice left at the end, though I had a blister between two toes.

The Olympic is a 5k run, 40k bike, 10k run. Because I haven't run more than 8 miles in one day, that's where I feel this distance is a little more questionable. I have no doubt that the first run and bike would be rather easy, but I question my staying power for the 10k run at the end.

I suppose the question is whether I want to just FINISH my first duathlon or potentially PLACE in my first duathlon - since it is my first, I am a little more inclined to go for the Sprint distance (and I would undoubtedly be doing the sprint were I doing the swim.. I am NOT ready for a 1500m open water swim yet), but I also don't want to sell myself short. Why not compete for almost 3 hours instead of less than two? If all I REALLY need to do is finish and get a time to beat next time (yeah!), why not do the Olympic?

I need someone to push me to enter one of the two, and I'm asking you ladies for some help. My boyfriend is frustratingly neutral on the matter ("do the olympic if you want to") rather than objectively telling me whether he thinks I am capable of it. Since he's my training partner, he'd really be the best person to tell me either way.. but he staunchly refuses to say anything. :P

Note: My next chance to do an Olympic distance would be Aug 1, then possibly Aug 22, and my goal for the year is SavageMan on Sept 20 at the Olympic distance. I kind of want to find out if I can do the bike/run leg this early in the year, so I can then focus on swimming (ugh) until the next Oly in August.