Can only suggest checking
Airline Seating Charts, Best Airplane Seats - SeatGuru first to check the seat pitch and configuration of airlines to compare who will best suit your lofty stature before booking (this doesn't cover all airlines, particularly not charter ones).
Booking early enough it might be possible to select your own seat. In June we travelled LHR-BKK with Thai and because we had booked early I requested (and was granted) 69 J & K so we got a row of two seats rather than three. This was primarily because we wanted to avoid climbing over another passenger to get into the aisle but the bonus was I got extra legroom, where there was a gap between the seats in front and the window. All because I looked for the best seats on Seatguru first.
Some airlines not listed on Seatguru will have their own seating plans online (eg. Thomas Cook, with whom I've reserved MAN-CUN seats on the A330, again with just two seats in the row instead of three).
Good luck.