Lake Hotel is the "big yellow lodge" on the lake. And they always suggest reservations for dinner. For breakfast & lunch it's not necessary. Same with Old Faithful Inn. Their dining rooms do have very good food, and are pricey - just FYI.
Lake Hotel is not the same as Lake Lodge, and Old Faithful Inn is not the same as Old Faithful Lodge, by the way. The hotel and inn are the "nice" places to eat; the other places have cafeterias. Lake Lodge cafeteria is our go-to place when we're there; food quality is really pretty good (especially for a cafeteria) and prices much less than in the hotel. AND you have a view of the lake while you eat.
In general, any of the sit-down (and get waited on) restaurants in the park are pricey. Food is quite good, usually; at the beginning of the season there may be a little more irregularity, with new seasonal employees just learning their jobs. (There are a lot of repeaters, though, and many who have worked over the winter.) Snow Lodge is a very nice restaurant in its own right.