I have used Alamo many times and have never had a problem with them. Once I disliked the color of the car (I hate white cars) and they exchanged it with no hassle whatsoever. Another time, the car I booked was too small(my fault, not theirs) for the luggage, we told them about it and they upgraded us from and intermediate to full at no charge and said "have a great vacation". Have never waited more than 15 mins. in line, now I belong to Quicksilver and have no waits at all. I am out of there within 5 mins. The shuttle is not bad at all and returns are easy.
I have heard the bad experiences and believe them, but, I have never had a problem. I have never been hounded for insurance, but, there again, I don't have any speeding tickets or accidents and they will give you grief (any rental agency will if they check the driving records) if they find anything.
Also, it matters not where or how you book the car, most places will charge for additional drivers. Alamo does, even via a direct ressie. It is on the website.
My worst experience ever was with Hertz, I will never ever ever use them. They only had one strike, but, it was a bad one.

Just wanted to say something positive about Alamo.
Gail
Offsite - 88
CBR - 89 & 90
PO - 91
OKW-92,OKW-93,OKW-96, OKW-97 2X'S,OKW-98 2X's
OKW-99 2X'S,OKW-00 2X's OKW-01 1X
Jamaica-SandalsInn 98&00