My bride and I just did HAL's 14 day Alaska itinerary out of Seattle, which includes a full day in Anchorage. I’d like to recommend reasonably priced, very helpful Downtown Bicycle Rental, (907) 279-5293 · 333 W 4th Ave; and the coastal trail. My wife was very nervous about riding a tandem, but they worked with us until she was comfortable, and we had a great experience and feeling of accomplishment when we made it up the hill the last half mile or so of the trail. There are many places to stop and watch critters, take in scenery and get a little history. The cost is much less than a budget shore excursion, and you get great exercise to boot!