Mendenhall is a nice hotel and the restaurant is entirely adequate. If you are "foodies," there are much better choices within a 20-minute drive; happy to advise. But "a good restaurant" is just too vague -- if you can be more specific about what you want that would be great.
There's actually a fine dining restaurant at Longwood -- 1906. It isn't open for dinner now that the summer season is over, but you can have a lovely lunch there. There's also a decent cafeteria.
There are also many other good choices for lodging, both less and considerably more expensive than Mendenhaall Inn. Hard to beat Mendenhall's convenience, but there are a couple chains even closer to Longwood.