If you are going for Shabbos Cinnamon Red is a problem because of the electric doors and the rooms don't start until the 10th floor so you need to walk up a lot of stairs. There is B&B Casons which is next door to cinnamon red and across the street from Chabad. It is not as nice as Cinnamon Red but it is clean and there is no problem with any of the doors, door to your room is a key and the highest floor is the third floor. The only problem is that the rooms are noisy. You need to ask for a back room and even then you will hear the cars from the street. I would recommend for shabbos, if you are going to be there longer, I would suggest staying somewhere else. But I will reiterate what emkay said there really is not much to do in Colombo so unless you have reason to no point in staying there much longer then Shabbos.
We stayed in Ella in 98 Acres Hotel, it is expensive for Sri Lanka, $180 a night (can get rooms in hotel for $75 and b&b for even less).
However, if you are going for one night and want a stunning view and something really special this definitely was. When you stay at this hotel you are half way up to mini Adams Peak so instead of having to climb there at 4 am to be at mini Adams Peak at sunrise, you get the same view from your bedroom window. The only problem is we couldn't book online, not sure if wasn't available or officially needed a two day stay. But we called when we got there and luckily they had availability for the night we needed. Could be if we would have called earlier would have also been able to book not sure.