@Amber635
It's a tricky one, but it really depends on your market. Why, for example, do you think you will be hosting guests who are grieving?
Personally, I find that the majority of my guests absolutely adore the Christmas tree. I don't really go in for other decorations but I do make a real effort with the tree and guests appreciate it.
However, one Christmas I tried putting cards, little gifts and treats in the rooms and found that, apart from a few guests, it was just a waste of money. Most did not appreciate that at all and some just chucked it in the bin without opening it...
So far though, I've never had anyone mention being offended about it. Here in London (or the UK generally) one would be surrounded by Christmas decorations and other reminders of it everywhere you go, so I doubt guests find it at all odd to have a tree or some decorations in the listing. It is just part of the local culture. Personally I think that people should embrace local cultures, not be offended by them.
I am actually not a Christian myself and was never raised at one (quite the opposite), but it's just part of my local culture and I don't find that offensive at all.