We've recently moved from the J.W. Marriot in Beijing to the Renaissance Hotel. I was never able to get a Beijing layover during the J.W. era, but I hear it was pretty good. With the bar set high for the Beijing regulars, the Renaissance has it's work cut out for it.
The rooms are great, with a hardwood foyer, and a fluffy comfy bed. There is a big screen LCD and free high speed internet (just charge it, and they remove it from the bill at checkout).
The bathrooms are great. The shower has both a handheld showerhead and a rainforest-type showerhead above that can operate simultaneously. There is a big standalone tub by the bathroom windows, which look into the bedroom. There are motorized shades that lower them.
Probably the neatest thing about the hotel is the gratis food and beverages. There is an open bar and hors d'oeuvres on the 24th floor. The food is served until 7:30pm and the booze flows freely (literally) until 9:30pm. In the morning, there is a complimentary breakfast in the 24th floor, as well as complimentary admission to the buffet on the 4th floor, which I only learned about until eating my fill on the 24th floor. So, unless your taste buds are bored, you'll not need to spend much on food and drink during your Beijing layover.
Be prepared to be surrounded by the local massage and spa folks when the bus pulls up. They'll follow you up to the lobby (on the 4th floor) as they hand out cards and try for your business. I got a 1 hour in-room massage for 100 yuan, and if you want more attention than the norm, the price will go north from there. Just let them know the time, and they'll knock on your door promptly and get to work.
The van to the Peal Market works a bit differently (apparently) than other hotels. This one was a small 12 pack van under contract by the Pearl Market. It left full for the 15 minute ride to the market. I didn't get a schedule, but was able to figure out the one of the pickup times for the return was 1:30pm at the front of the Pearl Market, perfect for the pickup time.
The fitness center and pool is on the top floor, and is fantastic. Very well maintained machines, and a wide range of dumbell weights. There is a squat cage also. The pool is a 25M lap pool on the same floor, but hang a right at the desk instead of a left. So, if you're into swimming, be sure to bring the goggles, speedos and cap!
Overall, a great hotel! The regulars will say its a step down from the J.W., but don't let these naysayer comments sway you. The Renaissance is no slouch! All things considered, I'd still rank it as one of the best hotels we stay, maybe even taking the top spot.
Have fun!