First off, well said natrass!
To answer your overlying question, I took advantage of American bookies because they offered much better lines on a few selections (for me it was global novelty markets, and basketball), now I think of it this is probably where most 'arbitary' betting situations come from too.
Being resident in the UK, I offer my own experiances.
From what I can see, European bookmakers (Stan James, Sean Graham, William Hill, Bet365, Labrokes, Blue Square are the ones I use/have used)
Pros
- Often high grade customer service
- Often regulated by gambling countries that have a certain amount of legislation protecting the punter and bookmaker
- High quality sites
- Ofter service is offered from long standing bookmakers (like Stan James or William Hill) and so these books have a higher liability should they get it wrong.
Cons
- Fixed odds, from my own research you'll be lucky to find more than 5% difference in different books prices, they all seem to be well in touch with each other
And, US bookmakers (or US serving bookies should I say), (I have used SportingBetUSA, Bodog)
Pros
- Better covourage and lines on less global sports, like collage basketball
- better odds, they may set their book higher than most euro-bookies
Cons
- Often sites are shabby
- Ofter there are regulations, terms or conditions that favour the bookmaker explicitly (eg "We reserve the right to change any price, any time, without notification, even on pending bets")
- Like you said, their "bonus culture"
- Poor Customer service (please note I found Bodog the exception)
- Payout issues
I'd like to stress that these are all IMHO, from my experiences. And I'd assume the difference comes from the culture in which these different bookies emerged.
The european ones, especially the UK ones, where set up either by existing legal bookmakers from europe or by people who understand the legal betting culture within europe
Whereas inversly, as America has laws against gambling online (The Federal Wire Gambling Act, I think its called), so consiquentally, the people trying to set them up are people looking to circumvent or flout the US law, and as such set up in a country with enough 'liberty' for them to get away with it. As there already into something 'dodgy', what's to stop that 'dodgy' attitude re-sufacing in the way the bookies operate?
Hope you find this useful!
ZuluWarrior