Help me choose my "A" race

There are pretty much 2 seasons for Tri's here in Las Vegas... early Spring and early Fall as Summer is WAY too HOT to do racing... So, due to injury, I missed the Spring season Tri's... So, I'd like to get some races done in the Fall... I have 3 on my list, but am having trouble choosing an "A" race... btw, this will be my FIRST ever Tri!

I just signed up for a 180 mile Relay Race on October 9-10 with my Running Group - of which I'm doing 3 legs for a total of around 12-15 miles, and I'll be doing the LV Half on December 6.

So, do I make the 1st Tri my "A" Race or the 2nd one 3 weeks later or the 3rd one 3 weeks after that, but 1 week after the Relay?  I think the 3rd race is the hardest course, but I have a training group for this one... and the 1st and 2nd races are similar courses. 

Thanks!

Edit: I allowed multiple answers if you think I should do more than 1 A race... stupid huh?

Edited by Cardholic 2009-06-26 4:51 PM