Two Questions... Location And Maid Of Honor

I have two questions...
The first is that I`m looking for a relatively inexpensive place to have an outdoor wedding around the Chicago area. The minimum number of guests is going to be around 150 because of large families. I have a while to look, so I`m not real worried. But I`m wondering if anyone has some suggestions?
Also, I need advice about choosing a maid of honor. My sister is getting married this summer and she has asked me to be hers. However, she lives in California and I don`t consider myself very close with her. I have a friend that I`ve been close with since I was in junior high (about 9 years) that lives about 5 minutes from me. I think I want to ask her because she will be able to help more with arrangements and knows me better. But will this look bad if I don`t ask my sister? What do you think?
Thanks!