We planned on flying Frontier for our September trip due to the cost (about $120 RT, less if we get a sale). However I'm reading a lot of really negative reviews about long delays, cancellations etc... They only offer one flight per day which has me worried. So now I'm wondering who to book with (flying out of New England - Portland, ME ideally, but Portsmouth, NH, Manchester, NH, Boston, MA, or Providence RI are all options). Looking at Delta, which right now regular price is $255 RT. I really can't afford to go any higher than that. With that - which airlines do you recommend, and when should we book to get the best deals?