This luxurious, 110-room boutique one block from Union Square is an enclave of posh rooms and pampering service in a dense city. There aren't many features here -- just a gym and a small business center -- but its top-notch service and luxe room amenities make it one of the city's most special hotels.

Not as conventionally luxurious as some Union Square-area competitors, but so filled with interesting touches and thoughtful extras that you won't notice. The rooms are smallish but have wonderful beds, quirky-yet-elegant style, and state-of-the-art technology. The service is rock solid. And the lobby is a great place to hang out, especially for the free wine receptions and morning coffee.

Clean, affordable and quiet, the Hotel Nikko seems more like a boutique hotel than the mid-size chain it is. Its cultivated Japanese-luxe image, apparent in the lobby and pricier suites, doesn't quite extend to all of its guest rooms (though most were renovated in 2012 and are more attractive than the older ones). On-site, for the business set, there's an excellent lap pool, fitness center, and ample business services.

After its 2009 renovations, the big, bustling, 1,010-room Parc 55 hotel has some great, modern touches -- big HD flat-screens, an extensive contemporary art collection, and top-notch equipment in the fitness center. It's a fine choice for Union Square, four blocks from the theaters and fashion boutiques, but the nearby Marriott and Hilton hotels are both very comparable.

Near the designer shops and theaters in Union Square, the 400-room San Francisco Marriott reopened after renovations in 2009 to show off new guest rooms and a new fitness center. It can be a great deal, especially when it's compared to the two other Marriotts in Union Square, but unlike many mid-range hotels, there is a pesky fee for Wi-Fi.

The St. Francis combines the history, decor, and traditions of a turn-of-the-20th-century grand old dame with the amenities, modernity, and corporate-dominated clientele of a large chain property. If you find a better deal at the similarly priced Palace or Meridien -- also business-oriented Starwoods -- go with one of those. If not, the Westin is a perfectly pleasant option.

Known for its Redwood Room bar, the Clift's hip scene is typical of the Morgans Hotel Group, which bought the historic hotel from Four Seasons and reopened it in 2001 after a makeover by Philippe Starck and Ian Schrager (the latter of Studio 54 fame). The lobby and the 350 small but comfortable rooms are short on amenities but high on scene and style.

This 660-room Hyatt offers all the standard amenities of a mid-range city hotel, with a few extra touches. Its Union Square location and spacious rooms make it a good choice for business and leisure travelers who want a lot of comfort without paying top dollar. This is especially true after an extensive, multi-million dollar renovation in 2012, which brought new decor and amenties to the rooms, a new restaurant concept and food truck, and a lobby revamp.

The JW Marriott -- the chain's high-end brand -- tries to keep pace with the town's luxury standard-bearers with touches like 24-hour butler service and 42-inch flat-screen TVs in the spacious rooms. But with unremarkable room decor, no destination restaurant or spa, and so-so service, the hotel is just a better-than-average chain hotel.

With 1,908 rooms and meeting space galore, this is the largest hotel in town. Business features are impressive, the restaurant is surprisingly nice, and the gym is well equipped. But rooms vary from impressive to so-so. Crowds of convention goers and business travelers make it difficult to find peace and quiet, or to get help without waiting in a long line.