athena or age group

If the weight minimum is less than your weight, you should consider Athena.  It's not mandatory and there will be much heavier ladies racing Age Group.

I prefer to race Athena now after trying it because, yes, I usually place better.  Often Athena gets to go first (fat = slow = need more time), which I like too.  I weigh the same as you, although sadly I am a few inches shorter

There's a great debate on this site about athena/clyde versus age group.  Many think it's the group for fat, slow kids.  I disagree.  I was beat in a recent race by a woman your size.  She was tall and strong and ranked very well overall.  The theory is basically that it's "harder" for bigger people to do the same things as the littler people.  Esp with running, us "big kids" (I say this tongue in cheek) have a harder time.  

I think it's fun to race Athena when you don't look like you're overweight.  Then everyone ask you why you're in the group and it's doubly good for my self esteem.

Long story short, it's really up to you.  But you shouldn't feel bad about your choice either way.  You're not cheating by putting yourself in a smaller group of competitors, but you are also welcome to be in the Age Group if you wish.

Good luck!

Few races have a "novice" category in our area, I'm not sure if that's more prevalent elsewhere.   In my area, the Athena group is generally not newbies.  They are more experienced and jaded ladies   It is always a very small group and while it's easy to place high, you can also be last.  I have been 3rd and last, all in the same race.  That's the nice thing about AG - lots more folks that will probably be slower than you

But back to the OP again - you can race in any category you want.  Most  of us that race Athena do so to place better or change your overall position (i.e. start times) and not because we need special help.  That's based entirely on word of mouth.    If you'd rather just go with the flow, then race AG.

One very imp point I didn't think of, mentioned by another, is that racing as Athena takes the age quotient out entirely.  That is the benefit of AG - racing with others the same age.  For me this is not an advantage since 30-34 is a fast AG.  If I were in my 20s, for instance, I would definitely race AG.