Yet another tread about my trip to the states soon. Sorry guys.

I'm looking into Sat Nav for my journey and wondered about using my phone (I have an iPhone 5 and the Sat Nav function in google maps is excellent in my view).

Trouble is, I'm with Three and they don't have any sort of add on package I can buy for data in the US (nothing outside Europe, in fact).

I know I can hire a Sat Nav over there but I like the idea of using my phone as it means I'll also be able to look for things like hotels, etc. and access my emails (and I'm wondering of doing it this way will be cheaper).

Anyone know of any good sim only deals which would be good for this sort of thing?

It would have to allow data roaming in the states (and not cost £3 per megabyte which is what Three will charge) and I'd only need it for two weeks (so no long contracts).

Have a look on Yank sites and see if they do SIM only deals?

Yup - good thinkiong. When I travel with work to the US, I often get a £40 warning in just over 24 hours on my Vodafone work BB - ridiculous

I always buy local pre-pay sim card with net access when I get top my destination. Obviously the phone needs to be unlocked to accept the sim, and reasearch the options/costs between the various providers before you go.

If usually stick my UK sim in an other phone so I can still receive calls etc if I need to.

Do you have a TomTom? Costs under £30 at the mo to buy the US maps and load them on - costs way more to hire a satnav or roaming. I have just done this for my US trip in Sept, £34 to get US, Canada and Mexico (and I'll get a couple of quid back through quidco). I assume you have POIs on overseas mapping

Mobile costs are much higher in the US

If you have a firm route planned, I would strongly advise booking hotels before you go, just turning up on spec can be very expensive.

Quidco often have 12% cashback on hotels for Expedia

I have a pretty high spec Tom Tom (albeit a few years old now) but I was given it by a chap who got it from a chap who follows those lorries that are always shedding their cargo.

I'm a bit worried about plugging it in to the Internet in case SWAT come crashing through my front window.

Seeing as never use it these days I might just plug it in and see what happens.

We were advised by a travel agent friend to book hotels for all the major places (Vegas, Yosemite, San Francisco) but we've just gone and booked everything I'm advance for convenience. It means I can take a good old fashioned map for back up and mark out in advance where we're headed.

I'd get all the routes from Mapquest in advance, turn by turn instructions. US freeway junctions can be confusing, especially those crazy left side exits!

You'll need to register the TomTom on their site, think you need the serial number

Doing some more digging and I found an iPhone app called Navfree GPS USA which has great reviews. The maps are downloaded to the phone so it can be used with data roaming turned off (IE. no charges).

I'll probably print off turn by turn instructions as well as a back up.