A few of my clients have Sony HD Cameras and are constantly asking for assistance on how to import video into Premiere or other video editing programs.
Most of the newer Sony\Panasonic Cameras (it seems) record to a transport stream format of AVCHD in a .MTS container. Adobe Premiere and other video editing applications cannot import this format so the easiest way I have found to import these types of videos is to convert it to an industry standard format that is supported by Premiere prior to importing.
My preference would be MPEG2 as you can keep the quality quite high in the conversion and MPEG2 is supported by all the popular video editing products out there.
To do the conversion I stumbled across a great piece of freeware from Koyote Software called Free HD Converter which will convert MTS easily to MPEG. The quality & size is adjustable before conversion and an additaional great feature of this software is you can queue a heap of footage files together and it will batch convert them all.
If you keep the bitrate, and resolution at the defaults like in the image it does a great job of retaining HD quality footage for Premiere.
** Update 22-10-2014 **
While not free this one has proved to be very good also and i’ve used it a few times now: mtsconverterfree