I'm wondering if anyone has done this before and can share any tips? What to look out for? What expenses would I have that differs to the UK?
I'm currently living and working in London, have a wife and child. My company has an office in Newport Beach and is looking to relocate me there; so this is less about VISA, but more about lifestyle, tax etc.
Appreciate your help as always
After you get a US bank account you'll be surprised that you can't qualify for a credit card because you don't have a credit history yet. Be prepared to pay 500 USD into a separate account which gives you a credit card with 500 USD/month limit. So you'll likely pay with your UK credit cards for a while and the exchange rate is a cost.
Your L1 visa (I assume) should be not problem, getting a US driver license is easy. In the first week setup an appointment with the social security office to get a social security number, it's amazing how often one needs that number.
Pretty open ended question. My main advice: make sure you get a big raise between your UK salary and your US salary. In the US salaries are usually higher, but you'll have more expenses.
I'm originally from Europe (not the UK), and I like to say (even though it's not completely accurate) that most countries in Europe are "all-inclusive": high taxes/contributions, but you get good services for free (good schools, day care, health insurance, etc). The US is more "a la carte": lower taxes, but you have to be responsible and pay for the services that matter to you.