I just booked the March 23 INFINITY sailing from Ensenada to Hawaii. We are staying one night in San Diego prior to the cruise.
Anyway, I used Priceline and selected a 4-star hotel for downtown. I was awarded the Grand Hyatt overlooking the harbor for $85. Not bad! I pulled up the Hyatt website to check rates for the night, it was over $250 for one night, so I feel I did well.
I'm also using Celebrity's transfers down to the pier in Ensenada, but they only leave from the airport. The hotel is close enough that a taxi will not be expensive.
Good luck with the hotel.