assuming rates and proximity to airport - this is really the one and only solution for "need-to-wait-for-another-flight" night (it wasn't particularly my case, but very similar). Staff was really friendly and helpful, but room itself left a lot to desire (high enough temperature of hot water for example :)). Breakfast was OK - it for some reason reminded me Holliday Inn in Riyadh, Saudi, but with an attempt to look cooler.

Close to the airport. Lovely swimming pool and health spa. Just as well cause the food is delicious and plenty of choice. Don't miss the buffet on Friday and Saturday. Lunch is huge, dinner is large. Great choices from Asian, International and traditional. The expats go there regularly for a treat. It is a fair walk along the beach and would not advise it in summer, but taxis are cheap and plentiful.
A must see is the local Doha market or Souk. You can purchase the local pearls very cheap and a must buy is the oil based perfumes. Be prepared to bargain hard. Also have a coffee or try one of the many Shisha (Tobacco Hookah) flavours. Take a trip to the sand dunes in a four wheel drive or motorbike for that exhilarating rush or just relax round the pool with a beer or cocktail.

stayed at this hotel on business end of january for just over a week, glad my firm picked up the bill. hotel was very clean and tidy if you did not look to closely.the food was very pricey , but good , the asian was brill. drinks seem very expensive, cheaper by the pool tent.
the breakfast had a very good choice and the staff was very good and was always on hand.the hotel mostly caters for business types as it is closer to the airport than the city of doha. but a trip into the city is a must, the beach is very large and plenty of seating area's. the beach area is good as well.get a room with a view of the bay,,fantastic at night.
good hotel and clean but can be pricey.
going back there in march , see if it has changed closer to the holliday season .

Hi, I stayed for 3 weeks on a business trip in the Marriott Hotel in Doha (there are also Marriott Executive Appartments and Courtyard). The hotel has a huge pool outside, right by the beach. Unfortunately almost impossible to use during winter time due to chilly winds. Good but not spectacular food in their restaurants (especially breakfast, for example, I would have expected more sortiments of cheese).
Gym is good but not very big, lounge is good as always, but you are restricted to 3 alcohol drinks per day(regardless of your status).

As major cons:
There is a huge problem with the noise - the hotel is located next to the airport so basically you hear all day and night planes taking off and landing. Taxis are a nightmare in the city, they are almost non existant and the hotel does not really help finding a taxi.

In general Marriott in the GCC countries ranks low in the preferences. People tend so stay here due to points and because of free breakfast, dinner and beverages in the exec lounge.