We relocated a year ago from London to the East Coast as my husband works in Changi.
I really can't comment on the West side at all apart from Newton Circus -my husband's boss lives there and seems pretty happy. The gardens and Bukit Timah/Tanglin are gorgeous but very expensive too. I think a lot of people like Holland Village too (I went there for the first time a couple of months ago and personally couldn't see the fuss but I don't think I stayed/explored long enough to do it justice)
We moved with a 3 year old and I'm 4 days away from giving birth. Just to reassure you the private healthcare is excellent - it has been such a far cry from the care received in the UK.
As for Singaporeans - we have a mixture of friends, but I'd have to say my closest friends here are Singaporeans now. I am good friends with a couple of the mummies from my son's school. We meet up weekly for playdates and lunch and help each other out. The only negative, not even that really, comment I've ever received from a Singaporean was a female taxi driver who thought we would be earning more here than we did back in London (which we don't).
We are really very very happy in Singapore - sure there are cultural differences but that's what makes it so interesting. I am still bewildered by the snack selection in any supermarket - dried what?! and if I'm feeling brave, I might even buy a packet. Driving is different, the speech is different and I don't mean bad either - just different. I love the coloured green lights for parking spaces in car parks, I like the way most things are so efficiently done and well thought out and I absolutely love the low crime-rate (our son is very active and I don't worry so much about him being snatched here) and the security and cleaniliness here. Food is a really big thing and I struggle with the humidity sometimes but can deal with it pretty easily by avoiding the hottest parts of the day to be outside. We also enjoy all the festivities and we're looking forward to National day and the fireworks.....
That's more than enough rambling from me! I don't think it helps with the original poster! but I just wanted to balance out other experiences here.
By the way, when I chose a place to live, I didn't base it on expat/Singaporean majority at all! I just used chose based on my own personal taste/style and proximity to my son's preschool.
Good luck with your decisions
ps. Now that I think about the most negative reaction I've had... I remember a few caucasian expat mummies that pretty much looked down their noses at me - quite unfriendly actually. I think some expats can be quite cliquey which may not help the overall opinion of expats in general. I look mixed (Eurasian) in that I can't be easily pigeon-holed so maybe that helps, but I doubt it-I think it's mainly down to attitude and open-mindedness.