Hi Bob
Several ways to do this but how big a discount on the rack rate you may get depends a lot on the time of year you're looking to book for and occupancy rates for that time.
You can the usual suspects on-line - Expedia, Opodo, Ebookers. The last time I booked the best discount was from $250 to $209 on one of these sites - cant' recall which one.
Alternatively, you can book directly with Universal on-line or call them directly. I enjoy the latter - you'll get their phone number from the website.
As for discounts, you can get one if you are an AA member - enter
AAA into the promotional code on the website. Think this runs at 10%-15%.
I've always found the best discount at the entertainment rate (try Entertainment.com) and by using ENT as a promotional code. Close to 50% discount. However, you need to buy an entertainment book (about $25) and this offers loads of other savings.
Last time we booked (July 2005) there were very few discount codes offered for the busy months though.
However, if there are 3 or 4 of you then I would still advice you to book at the rack rate ($250+ per night) for the Express Line benefits you'll get at both parks for 2 days.
Garry