A 3.5 GPA is equivalent to an Upper Second Class in the UK, so you should have no problem getting into a good British Masters programme at a red brick/Russel Group university.
Similarly, in Canada an upper second class honours will get you into virtually all their Master's programmes, so you should get in also.
Remember if you are from the US, you'll be paying 'international' level tuition fees at a UK or Canadian uni....so they'll be very interested in you.
I'd say you'd be able to get into virtually any uni apart from the very top ones.