As I keep saying to inquirers like yourself who have so many destinations and cannot give up any ... you're trying to pour a quart into a pint bottle. My recommendation is
(1) look at a map and realize what the "outliers" are -- off by
themselves, not on the way to anything, involve looong driving
time... especially important when it's still winter & dark comes
early. Your 2 are Meteora and Olympia.
(2) Ponder which has the deepest attraction for you and why, which
you've studied & know enough about so that the experience will be
important, vs. having just heard about it being important.
In my case, this process has led to my not going to Meteora despite 12 trips to Greece since '99 (don't mistake me for a luxe world traveler, I'm on a tiny pension, so Greece is almost my only trip). I enjoy the occasional church visit, particularly to ones important in Greek independence history, but am not a monastery buff. I've enjoyed seeing various DVDs with aerial views of the pinnacles with buildings perched on top, and admire the feat of hauling all those bricks etc up in baskets, but can't figure out why.
On other hand, I'd taken multiple upper-level and graduate courses in CLassical history, art & architecture, so the treasures of the Olympia museum attracted me greatly. Nonetheless, I didn't make it there until my 5th trip (solo) because travel pals on prior trips were "newbies" and not interested. I took intercity bus (V. good BTW) and from Athens Airport - Olympia took from 10 am-5 pm. My best tip was from my hotelier next AM : go to Museum FIRST, while bus tour groups are in the ruins area. I did & had a precious 90 minutes or so almost alone... left as crowds invaded. The ruins & stadium were OK, not as impressive as elsewhere IMHO, and harder to interpret despite prior prep. I've enjoyed the stadium in Nemea more -- and SO handy.. just 10 minutes off the highway en route to Nafplio.
Your interest in finding monasteries indicates the religious or Byzantine-art aspect is of more interest to you than Ancient stuff ... so perhaps you could trim your travel by omitting Olympia, at least on this trip.