I have two GPS loggers, and am very happy with both units.
The first one is a Wintec WBT-201, a very tiny unit with internal memory only, with Bluetooth (and an on/off switch to save battery if BT is not needed when simply logging to the unit) and the possibility to log a waypoint by pressing the other button. The unit can be configured using a Windows software, but once it's setup tracks and waypoints can be downloaded either via USB or BT (thought I've never used the latter). GPSBabel supports the unit nicely. The battery lasts more than 16 hours when logging without BT, and can be charged via the mini USB port. The device is very tiny and fairly flat, and fits nicely under an airplane window shade...
http://www.wintec.com.tw/en/product_det ... ?pro_id=65The second unit is a Locosys BGT-31, also small but thicker and more feature rich compared to the WBT-201. It has a nice LCD display with backlight, and a mini-joystick button, plus the on/off button. Plenty of different features are available, logging to both NMEA and SBN (binary) format. The display is a nice thing to have when riding a bike, for instance. Has an SD card slot for a card used for logfiles, is waterproof and battery lasts a very long time. Also has a mini USB port used for data up/download and battery charging. Fully supported by GPSBabel too.
http://www.locosystech.com/product.php?zln=en&id=30Lately I've been using mostly the BGT-31, as I like to read the SD card with the logfiles better rather than using an USB cable to download the data from the unit. But when I am flying commercial I use the WBT-201 to log the flight.
Ciao, Luca