I lived in LA for 7 years and used to do business all over so cal. I have to admit I was scratching my head trying to think of an area to recommend. Couldn't think of one area, so I pulled up a map. There really isn't a clearcut place to recommend. I honestly think in this case you are better off splitting your vacation between the two places. Downtown LA comes the closest to being an okay place to stay in between, but honestly I think you will hit traffic hassles.
I'd recommend Grand Californian at DL. I'm not a huge "Hollywood" fan and really the term Hollywood often is used to describe places that evoke Hollywood (i.e. studios) rather than the actual place itself (where Graumann's is). You might find more upscale digs in the Beverly Hills area i.e. the Beverly Hills Hotel, the Four Seasons, the Peninsula. In Hollywood, there is the Roosevelt Hotel - classic. Head towards W. Hollywood and there is the Chateau Marmont, Bel Age, Mondrian, etc. I don't know of anything upscale at Universal City but there is a Hilton and Sheraton there.
I'm sorry I couldn't be of more help to you. It seems strange that in the distance that there is between the two places, there is so little to choose from. But, IMHO, there isn't. Hopefully someone else may know of an area that I am missing.