What paperwork is needed (if any) for a visit to the USA for a holiday, either by car or plane? I am from the UK with a Canadian PR?

ESTA? By plane, at least.

If flying you need to get the electronic visa thingy in advance now. (ESTA)

Driving you would have to go in the office at the border to get the green I94W form ($6 US IIRC). I dont think you need the electronic advanced clearance, but I am prepared to be corrected by those with more recent experience (or the time to google)

You don't need ESTA for driving - however some have said they have got away with going into the office by having it.... That isn't the official line however, so may have been luck of the draw!

If you have PR in your UK passport, be careful - you might have the misfortune to be processed by a US-CBP officer, avec large chip-on-shoulder, who decides you are no longer eligible to participate in the Visa Waiver program.

For extra safety, if crossing by land, take a recent bank statement and/or utility bill as proof of address as well as something that shows you are in paid employment.

I dont understand... how does canadian PR affect your visa waiver status? Never seen that mentioned before.

They might be suspicious you are crossing to work in the states for your canadian employer, but that is equally likely for any one coming from the UK on a business related trip too.

Can't you just use your UK passport? Techincally even though you are a PR, you are still a British Citizen...this is what we did....and we all had a visa in our passports.

I may have missed the point of course (been a long day, and just done a hideous Step class)...and there now may be other things you need to provide since I went into the US from Vancouver in July this year...

it doesn't have a direct effect, but it does clearly show that you no longer have 'binding ties' (eg: job; house; family) to the UK and this MAY be sufficient grounds for the CBP to decide you no longer qualify for visa waiver program. Once this happens, one will need a B1/B2 visa to enter the USA.

I speak from experience - this is exactly what happened to me...CBP decided that I was properly resident in Mexico, not the UK, and no longer eligible under VWP.

I suspect that $$$ drives that decision - a B1/B2 costs at least US$150 for an adult.

Yikes, that would seriously tick me off... Still got 2+ years till citizenship!

You still need to show "nonimmigrant intent" with the B1/B2 visa. No different to the visa waiver. British citizens living permanently in Canada rarely have problems in this regard. Living in Mexico may not impress CBP officers to the same extent, especially if you have not got resident status in Mexico.

Canadian citizens can be - and sometimes are - refused admission to the USA for the same reason, lack of "nonimmigrant intent".