I, for one, bid in this order:
1. Efficiency (high value crammed into 3 and 4 day trips). If my 4 day isn't worth at least 20 hours I trade that sucker. I prefer to do 3 and 4 day trips because my drive to the airport is about an hour so I prefer not to do that more than once a week.

2. Days off. Because my girlfriend works part time and I don't have any kids to tote around, having weekends off is not a huge deal to me. If there is something I want to do on a specific day (GO SIOUX), I'll try and get that day off. Other than that, I don't really care.

3. Good overnights. Because food is expensive on the road, it is always nice to spend a day at one of the all inclusive resorts in Mexico where you don't have to worry about spending money. Plus its nice to chill on the beach once in a while. Or if there is someone out there I want to drop in on and visit, I'll look for something there too.

If you commute you probably look for 4 day trips that start late and end early so you can commute in the day off and fly home the night you finish. If you have a hot little lady your wife doesn't know about down in Mexico, you bid for that. If you wanna go to little Jimmy's soccer game on Saturday, you bid for weekends off. There are any number of reasons guys bid what they do so you usually get at least something you want.