I was doing some testing in my local shopping center this morning. There is a free public wifi service available which was showing 3 bars on my n97, the n900 did not even show it in the list.

Has anyone had this experience/got any suggestins?

Is there any difference in wifi between uk and us firmware as this phone from expansys is a us one.

There's a difference in channels allowed, yes. Not sure whether this is handled at the firmware level or by region setting though.

I know if I change the settings on my Netgear router I get fewer allowed channels for certain countries, the UK seems to allow all channels, can't tell you what the US allows. Your shopping centre could be on a channel not allowed in the US. Don't know if a re-flash to a different firmware would help as I don't think it helped people trying to get the radio transmitter working in countries that didn't allow it.

Where are you? Are you in the US or from the US? seeing how you spelt 'center' the US way.

Europe: Channels 1-13
USA: Channels 1-11
Japan: Channels 1-14

JohnWW
I'm in uk from uk, just can' type!

Sorry! - I'm English, I only know English and I've always struggled with it.
I don't know if you can get an app for the N97 which will tell you what channels WiFi uses (didn't load many apps on my N97). But you can for the N900 called WifiInfo in the fremantle repository, don't know if that will help.
I have never understood why the WiFi selection tool doesn't tell you - so useful when setting up a wireless network.