I was surprised to not find any reference at all to this venerable old eatery on Chowhounds.
Our travels last week took us out to the San Jacinto Monument, my first visit since elementary school. I'm pretty sure we went at least twice back in the mid to late 60's. I hadn't been there since.
We finished walking around the exhibits and grounds around 2ish, so we popped in to the Monument Inn to see what's what. It was fairly vacant at that time on a Wednesday with maybe 4 or 5 tables occupied besides us.
Ordered a dozen oysters which were excellent for a non-"R" month. Clean and briny, good size and texture. Yum.
We also split a bowl of crawfish bisque. It was meh to good, but quite frankly I think the version I often get at Pappy's, (occasional soup of the day), is much better.
We also had side salads which were not memorable save for the house made blue cheese dressing. For an entree, we split a seafood pasta dish which again was fair to good, but I'd get something else next time.
They are apparently famous for their fried seafood, but having just walked around the monument and grounds, I wasn't in the mood for fried.
We intended to take the ferry across to catch I-10 back out west, but by the time we finished eating, the ferry line was two or three trips long and I wanted out of there before rush hour, so we went back the way we came.
It was great way to spend a beautiful day playing hookey from work. If your Wednesday was half as good, we both had a great day.