GENERAL INFO:
We arrived in San Juan 3 days before so we could tour El Yunque national forest and Old San Juan. San Juan has dozens of hotel choices ranging by price. If you check Expedia.com they provide a list of hotels and give you the ability to sort the list by price or by traveler opinion. The latter is the way to go and you'll notice that Hampton Inn is consistently listed in the top 5, and its worth it. The choice of hotel really comes down to life style: some want more from a hotel and some accept less for lower price. Just remember that choosing a hotel is like paying taxes in the United States: you get what you pay for.
From the airport you can take a cab at a defined rate by zones, just ask the driver what it will cost, and also be aware it is posted at the airport by the baggage claim. From your hotel the next morning you can again hail a cab and pay a defined price to the pier. You can ask the front desk for info on cabs and typically cabs hang out at hotels for morning travelers.