When traveling if you are willing to put up with the risk and hassle of getting your bicycle into/out of the airline system you can really save some money on cabs or car rental. I absloutly love my 2002 Gary Fisher Tassajara w/disk brake bike. Dont be the sad guy/girl and loose your bike it may be the nicest one in town depending where you stay, I park in well lit public areas or better yet private homes or protected courtyards, I always use both a U lock as well as a kryptonite cable through the wheels, I always carry a spare key in my wallet with a neck string so I cant easily loose the spair. A way to camoflauge the value of your bike is by covering it with stickers and tape/wire it makes it appear much older and will divert the eye of theives.
I am currently considering adding a part time gas motor for when I am in places without a car, 35mph sustained sounds nice to me when I am wiped out. Some schools of thought buy into the 4 stroke honda gx31 motor others just use a 2 stroke and don't worry about the noise or exhaust. Some advocate friction on the tire drive others will tell you to use a chain or belt drive. I dont see electric being a usable option for me because while in the city if you dont like to peddle they are great, I am thinking more of rural big hill assists where the power plugs are far between, and bike batteries weigh too much to drag them up a hill after they die, besides I like to peddle when it is possible.
Bike Specs: Fisher silver grade aluminum frame, Rock Shox Judy front fork and seatpost, Hayes cable disk brakes, and Shimano Deore drivetrain. In the bike under saddle pouch I carry
Tire levers
Crank Brothers bicycle tool (screwdrivers, Allen drivers, spoke and chain tools in a fold up gadget)
First aid stuff (4x4 gauze, tape, Arnica Montana anti bruise/muscle, codeine/muscle relaxant, Vivarin, Neosproin, Bandaids)
Spare mobile phone batery
Cliff bar (OU kosher!!)
10 pack bus/light rail tickets
Tube repair kit
Spare tube
Cash and change
On frame:
Bicycle pump
Water bottle
LED flashers (red and white)
Marwi Nightpro headlamp with totaly redesigned/rebuilt battery pack and more powerful bulb
Seatpost suspended tailrack (I need to figure out a way to keep this from swinging into the tires)