I'm from the Northwest of the US, which I think has given me a slightly softer American accent, or at least really throws Brits who are trying to guess American or Canadian--apparently lots of them play this game with North Americans. I am currently living in the Southwest of England, so I like to pretend that with all these West Country accents around, making their 'arrs', that I don't stick out too much. In reality, I regularly get asked about my accent at work (waitressing), and yesterday had a couple search me out to ask about my accent because they had spent most of their lunch discussing it. I've found the best approximation to my accent (to my own ear) was a lady I met in Australia, who was a Canadian from BC, had married a Scotsman and lived in Scotland for a bit, and then moved to Australia. She described us as sounding like a mess!
My (English) boy and I have both noticed that we speak much more clearly than we used to from being around each other, but he has trouble listening to me speak to my American friends from home, and I have trouble following conversation between him and his friends from home. Or rather, I can follow it eventually, it just takes me so long to translate it that I can't join in.
I've found myself having no problem translating words from British to American in my head, like "tap" to "faucet" or "boot" to "trunk", but I don't reach for them when constructing my own sentences. I'll talk about the zucchinis and reach for the courgettes without batting an eyelid. My husband thinks I'm being stubborn and refusing to pick up the lingo. : )