You will be sorry you have picked ATP. The quoted time they give you to for the program is not true i studied and had all of my writtens done before i started the program and never finished on time.Planes were junk and always broke. 2 months after i started the program i had a checkride scheduled for the day i was supposed to fly back to New york for my sisters wedding. Even though i told them i would be going back for 2 days and that everybody else got a week off before starting the ACPP. Dave Shiffman the so called station manger called Jim Korzski in JAX and said i was dictating the program beacuse i was leaving for 2 days to go to my sisters wedding and they terminated me from the program. Be very very careful of what contracts you sign 14,000 later and no private pilots license.
Sucks that it turned out that way for ya. For the vast majority, it's not that way - seems like Mr Shiff had a vendetta out for ya!
For the most part, for ANYONE, considering ATP. You really can't plan on taking any break whatsoever. That being said, you definately do get a couple of days off here and there, maybe even a week or two if weather becomes an issue - but you don't have enough certainty to make a ticket purchase well ahead in time to save you money. I worked @ Admin for a little over 2 months, and I remember it happening to 3 students. Same scenario for each - they SHOULD have been done by a certain date - so they bought tickets home. When the time came, there was a delay (imagine that in aviation) and they got into it with Dispatch/ ATP.
As far as the timing goes - some people finish the private program in a month or less, sometimes it gets to 2.5 months... weather and plane situations has a lot to do with and as you can imagine is a very flippant situation....
That being said.... it took ATP 3.5 months to finish my 90 day program up.... due to scheduling issues, and weather. Dispatch has a nicer half, and another half that is hard to deal with as a person, and admin is usually to busy to make everyone happy all the time. All in all, the consensus seems to be that ATP provides you with everything you need to get your ratings, but a lot of it depends on your effort as well. Patience is a virtue I suppose!
jac, just keep focused, and you'll be fine in the program. Knock out all of the writtens ahead of time if possible - it makes life a LITTLE less stressful for the 3 month period. Also, even though some locations teach you off a gouge, and some instructors want you to be thoroughly proficient(myself included)... absorb EVERYTHING you possibly can and don't just study to pass checkrides. There's plenty of ATP instructors on this board, we just gotta be as anonymous as possible ( You can imagine why

) All of us are happy to help.