If you want to drink your coffee from the same bottle you transport it in: I have the Zojirushi SM-SA48-BA Stainless Steel Mug (The Sweethome's top pick) and love it--the lid completely comes apart for cleaning but it does not leak at all--as long as you remember to lock it. The 2nd cup comes out just about as hot as the first in the mornings. Pricey but lightweight for having an insulated and leakproof lid.
If you are just transporting it: For absolutely no leaking and maximum temp retention, you can't beat an old fashioned thermos, the kind with the insulated lid that is also a cup. I have an older version of the Thermos Vacuum Insulated 16 Ounce Compact Stainless Steel Beverage Bottle and taken it hiking in winter in the Alps before with excellent results. If you don't put it in the dishwasher, it'll last for close to forever.
As with any thermos, if you preheat it by pouring in hot water for ~15 minutes before you refill with your main drink, you'll get the best temperature retention.