I stayed in Furama City Centre Hotel a few years ago; cost about €70/night which is ok if you are only staying 2-3 days which is enough time to spend in Singapore anyway
Singapore is a really nice city, very clean, people very friendly. It is totally unlike any other asian city you will ever vist; you would almost swear you were in Boston or Chicago.
In addition to the hop on hop tour, visit Singapore Zoo, it is one of the best in the world.
There are loads of shopping centres, not that I was interested in them