SALT has no view. The Kunlun restaurant does have a great one but go on a very clear day! Alternatively, try the Beijing Hotel lobby for afternoon tea with a view.

If you do dine at the top of Kunlun, the air is so polluted you can't see anything.

I stand corrected. You can see a few kilometers from your window a few days a month. Is the BJ Farmers Alamanac now including a pollution index, so we now know which days to dine atop over priced, sub-par hotel restaurants?
Seriously, if you really want a romantic enviornment go to Jaan at the Raffles Hotel. It lacks a view, but the environs are great, and the food is excelent. For a lower priced, domestic cusine option try Dali. It is a beautiful courtyard restuarant serving yunnan cusine located around Gulou.