I've stayed at the Sheraton Grande Sukhumvit at various times throughout the last few years. My last visit was in June of 2012, so this is slightly dated. I still wanted to give it a review as I anticipate I'll be back there in a few months.
The staff has always been exceptional during all of my stays. Last time, I needed to work through an airline issue, and the concierge went above and beyond to try to make the air travel adjustments. The issue was gettting in touch with someone from the airline on a Sunday. He did everything possible to do it, finally with success. The staff has always been helpful. I am anxious to see if anything has changed based on a few reviews.
The location is very good for central Bangkok. The Skytrain is right across the street and it is one of the best ways to get around during peak traffic times in Bangkok (which some would consider to be all day). This hotel is not near the river. If you want that in a Sheraton property, try the Sheraton Royal Orchid Hotel. It is very nice as well. It is just not as central as this hotel.
The rooms are quite comfortable and I've always slept well here. The bathroom has plenty of room for 2 people and the seperate bathtub and shower are helpful. There are plenty of food options within walking distance of the hotel.
I must agree with one of the other reviews I read about the pool. The pool area is rather small and the pool is not a lap (or large swimming) type of pool. It is adequate for a quick dip, but that's about it. If there was anything I'd change about the hotel, it would be the pool area. The setting is comfortable and nice. It's the confined space/area that hinders the usefulness of the overall area. It is Bangkok, and space is at a premium. So, I guess they work with what they have. All in all, if you want a few days poolside or beach side, hop on a quick hour+ flight to Phuket or one of the other many beach areas in Thailand and get your fix that way. Bangkok is vibrant, exotic city. Get out, live it, and enjoy it!
I would recommend this hotel due to the location for business travelers or touring the city. I'd also recommend it for room comfort and staff.