Robyn, you never mentioned how you got on, but my $0.02 for what it's worth...
- Main St banks in the US (you mentioned BofA) generally are appalling when it comes to foreign exchange of cash. Avoid them where possible.
- Bringing USD with you and changing it here would be fine. Money changers in Singapore are honest. If they deal in fake money or any other shady business, they get in VERY serious trouble. Extensive competition means the rates are very competitive.
- Small shops will likely be cash only. If you wanted to use credit cards for larger purchases, you won't have a problem. But that volume of cash would be fine for the time you're in Singapore I think.
More importantly, enjoy your trip
