Hello my name is ***** ***** I am delighted to answer your questions today. I have 35 years experience as an immigration lawyer.
You have two options. You can file for US naturalization. You are allowed to keep your UK citizenship as both countries recognize dual citizenship.
This process wouldl take approximately 6 months and is strongly recommended for both you and your spouse who may keep her dual citizenship as well.
Second option is for you both to file form I-131 for a re-entry perit
This allows you to remain outside the US for up to 2 years. It can be renewed once.
Bear in mind it is only good for one entry. So if you come across the boarder in 3 months it is rendered as "used" and you would have to file for another one. This is really meant for people whose jobs or family circumstances take them abroad and who cannot easily come to the US across the border. It is an expensive option and would probably not be effective for you if you have any ties here that would bring you back and forth.
This process takes 90-120 days.
So your very best option is the naturalization. It is cheaper than filing over and over again for re-entry permit on every entry and having to sit here and wait to do biometrics which can take a month or two for an appointment.
Experts are only paid for their time providing you a low cost alternative to getting immigration law information if you RATE their answer. Everyone likes to think that their time and knowledge has value, I am sure you expert to be paid at work for your time and knowledge. It is no different for an expert. No rating, no pay. May I answer anything additional for you to earn your satisfaction. I strive to give good customer service and comprehensive answers. I feel I have failed you. Please tell me what additional information would be helpful.