I find ET to be fine, just keep expectations low. They seem to delay a lot and swap aircraft at will but service on board is decent, food is decent. They don't maintain the interiors of the planes so well, so the 767s are beaten up pretty badly, the 777s and 787s are getting there as well. Addis airport is a pit but you're going to deal with that regardless of the airline you fly long haul if you're going to LLI.

As for booking, most likely will have to use a real travel agent for mix class bookings. Unfortunately most online sites won't/can't do it.