Yup, that's the same Keio Plaza which seems to have changed affiliations. No more "executive card," it seems.

The Keio Plaza, Tokyo Hilton, and Century Hyatt are all close to each other and all are decent upscale hotels. The Hilton and Hyatt run regular free shuttle busses to/from Shinjuku station. Keio doesn't, but that could be because they own a bus company that has stops next to the hotel. All three hotels can be reached from the station in ten minutes walking max.

I don't know much about the Le Meridian, but I suspect the Renaissance Tobu is of a lower standard than the aforementioned three hotels and hence not as good a buy at the same price.

I disagree with the previous poster who said all the department stores are on the opposite side of Shinjuku -- Odakyu, Keio, and the wonderfully named "My Lord" department stores are all on the west side of Shinjuku (like the hotels). Lumine straddles the station. There is also Yodobashi and Sakura camera which are WAY more than camera stores. But you will want to take a trip to Akihabara to look at the main electronics district.