Legroom is always a biggie when it comes to plane seats. First and business class seats are always roomier but in general legroom varies a lot depending on the airline and type of plane you’re flying in. JetBlue is known for being roomier than most. SeatGuru is an awesome resource for everything airline seat related. They’ve got seating charts for just about every flight so you can determine which seats you want before booking your tickets. This may go without saying but three areas to avoid are middle seats and seats near the galley or bathrooms.
It’s best to select your seats as soon as you book your tickets. The earlier you book, the better your seat selection will be. If you go through a third party like a travel agent or travel site, you’ll need to contact the airline directly to reserve your seat. You can also use frequent flyer miles to cover premium fees. Because of overbooking and other last-minute changes, you should confirm your seats 24 hours before your flight.