Hey Mark - I loved it too. I sort of heard Tom Petty and the Heart breakers doing this.

A couple suggestions:
The one thing that didn't go over with me (and I guess it's just me because nobody else noticed it) The very last verse, there's an odd toned guitar that comes in playing after each line of the lyric is sung. It drew me away from the words and the harmonies and as expected, heard a different riff each time with the weird tone guitar. I'd do a post mix - the part was good, but push that tone into overdrive and make it sound like you've got the pedal to the metal. Give it some distortion man, lower it in the mix, and tease my ears with it. Don't overpower the vocal.

2nd suggestion - you got me with "help me Rhonda" line just like you got everyone else. We get it the first time you sing it - the harmonies are spot on. How about instead of singing the same line twice (exactly like the Beach Boys) add something to it to make it become your own - like this (sung exactly the same, different words):
Help me Rhonda
Drive past the Honda

Take it or leave it - it's a subtle twist, it'll still sound just like the beach boys, but you now add creativity to the line and make it your own.

Tom Tracy
http://www.soundclick.com/tomtracy