Shibuya Excel Tokyu Hotel:
Tokyu Hotels - Shibuya Excel Hotel Tokyu
Cerulean Tower Tokyu Hotel:
東京・渋谷の宿泊はセルリアンタワー東急ホテルへ｜Hot el in Tokyo
Both are in Shibuya in really nice locations. Excel is pretty much where the main crosswalk in Shibuya is and Cerulean is about 2-3 minutes away from there, like half a block and across the street. Both are also just a minute away from the JR and subway station. I think the Excel has a better location, but the Cerulean rooms are a lot nicer, the hotel in general feels more high class, and less crowded. From the site, looks like the cheapest single room at the Cerulean is a 33,000 yen and Excel is probably around 25,000. Free internet at the Excel, and Cerulean charges 1,050 yen per day.
Those are the only two hotels in Tokyo I've had experience with but with the subway system close you can pretty much get anywhere you want. Plus, if you're looking for things to do, there's a ton just a step outside the hotel and the nightlife is just as alive as during the day. I know people like to recommend you travel outside Tokyo to really experience all of Japan, but if you're just going to be shopping and kinda hanging out, Tokyo is definitely my favorite place to be. Pricey, but if you can afford it, I've had good experiences at both hotels. (I've actually had a friend complain about the noise at the Excel hotel, but I don't remember having much problems. It is in the middle of a really crowded area though.)