I have flown the 737-800/900ER and now flying the 777-200/300ER. 800 seems to the maximum they should have stretched. In my previous company we have had tail strikes of 900 during take offs as well as landings due to excessive rotation, holding the nose off during landing for long time, incorrect weight/v speeds. And the damages are on the tail skid or sometimes on the fuselage, ripped apart.
If i remember correct tail clearance was 11 inches on normal take off flaps(5) setting. Which is way too low. Boeing has just stretched it too far and left very less margin for error. Even 777 300 has tail strike issue, but thank God the primary flight computer has tail strike avoidance system.
You should consider 321.