I third River Valley / Robertson Quay Rd area.
There are sections that don't feel as built up / urban as Orchard Rd. You said you lived in the country so you may prefer it to be little laid back. I personally find Bugis, Chinatown very urban. On River Valley Rd is Fort Canning park which is a small oasis and if you like running you can do a couple of loops of it and it's lovely. Plus, if you live close enough to walk to Robertson's Quay then you have maybe 30 bars, cafes, restaurants to choose from. That section of the river is more laid back.
You may want to check out condo
called Aspen Heights. They're refurbishing the pool until Aug and many units are vacant so landlords may do you a good deal. We know it well and it's a good condo with good grounds / feel and very close to Roberson's and city. You will need to go through an agent to find something anyway so first day consider going to see i) River valley, 2) Tanglin (which is near botanicals and start of Orchard) and 3) Orchard. Good luck