IMO the UK tickets are much better than the US tickets, certainly for what we were looking for anyway - hopping is free in ALL of them.
There are basically 2 main types:
Premium: any park, you can park hop, for either 5 or 7 days. If you get the 5 day ticket you get four visits to DTD, PI, TL, BB etc. If you get the 7 day ticket you get six visits to those. Upgrade to never-expire tickets for $55 (7 day) or $35 (5 day).
Ultimate: any park, park hopping and unlimited DTD, PI, TL, BB etc. These come in 21 day or 14 day lengths.
We got ours from orlando-ticket-deals.com who are VERY good. The price difference between a 7 day/5 day Premium ticket (Currently, there is no price difference between the Premium 5 day and 7 day tickets - so you essentially get 2 days free!) is £10 ($17). There's a £12 ($20) difference between the 21-day and 14-day Ultimate tickets. Even though we are only there for 8 days and a 7day pass would have sufficed, we ended up getting a 14-day Ultimate ticket because the £10 extra charge for an extra week of ticket AND unlimited PI/BB/TL was well worth it.
If you have someone in the UK who can recieve these for you and then post them over to the USA, why not do it? These are perfectly valid tickets and it's not like you haven't made the effort to get yourself the ticket best suited to you needs.