Ketchikan is a small town and the best way to explore it on foot. You can also take a taxi or rent a car if you want to visit other attractions outside the city. Taxis cost around $10-$20 per ride, and car rentals start from $50 a day.
If you have more time, consider taking a scenic flight tour or going salmon fishing. If you have less time, skip the Fish Market and spend more time at the Great Alaskan Lumberjack Show.