Shoot and master in 23.976 progressive segmented-frame. That is probably the format that will be easiest to translate to 25 and 29.97 should you need. To get to 25, you can either speed it up and pitch-shift audio to compensate or do an advanced format conversion with a hardware converter. To get to 29.97, it's simple to add pulldown either in software or the aforementioned hardware conversion.
Sverker, one of the great joys of living with PAL is that frame rates are simple. Mark's idea of 23.976 has a fundamental problem if you are producing programs for broadcasters. Speeding the program up to 25 changes the duration as well as the feel and pace of the program. Yes you can correct the audio pitch but in my experience it compromises the PAL version.
Remember, most of the world is PAL. Although the US market looks big and inviting, the usual path for distributing is to provide an HDCam at 1080 50i and it is hardware standards converted to 1080 60i. This is not the best result for the pictures but it retains the correct duration and audio pitch. In delivering many masters for international distribution, I have never had a requirement to provide any other format than HDCam 1080 50i.