Originally Posted by
bballdad175
.... What options do I have to get something similar to at least UA E+ for the long haul segment on those airlines?
Partners don't have an equivalent to E+. Some have a Premium Economy which is a different cabin and offers seating better than E+ (something like domestic F on UA or even better). However, most of them come with a significant premium over economy, so as mentioned the $300 (RT?) limit is probably going to eliminate them as an option.
And if you desire to or need to book on UA ticket, it will be very difficult if not impossible.