I built a retaining wall in another location on my property. I used the stack and fill block. Results were excellent, but it sure was costly. It's 5' high and about 35' lone with a set of steps. Cost was like $3500! The big block make for the nicest wall and can be done without much skill. Just make sure to get the first course level and the rest is just stack and fill (not that it's not a lot of manual labor).
I also built another one out of utility poles held in place with pilon posts. Works good and cheap, but not the prettiest thing (but not hideous either). Total cost $350 for about 2.5'x35'. And, once the pilons are set, it's a very fast build.
I guess you don't have room to cut the wall down to make a mowable embankment?