Some OneWorld summer holiday routes to the USA.

WT ex Germany

I know that California is popular in the summer and tickets are often close to £900 if you don't want to fly WOW! or The Cook named Thomas. You may even prefer OneWorld. You can fly exDUS with one stop on AA to LAX for £552 in July and August. Some slightly more expensive alternatives are available too.

From TXL you can fly to SFO for £461, but with two stops on the outbound. The inbound routes via LHR.

To Florida your best bet also is to start in Germany, with HAM being cheapest at £353 to TPA.

WTP to US - Germany and DUB

WTP to Florida exDE is available at £895 and slightly higher

For WTP to California the best deal (close by) is PHX (or SFO) at around the £1100 mark. Availability is limited.

DUB-USA for WTP is always a good bet and it seems to work throughout the summer. CA around £1100 and FL can be found around £900 to £1100.