In MML, if you type the letter L followed by a number that number becomes the default length of notes. So with this example, you could type L60 at the beginning and then omit writing 60 after any notes.
Adding a repeat would make it shorter. You wouldn't need the Label or WAIT command. So...
BGMPLAY "T121L60[[AA<EEDC>BAGAB<CDE&E30]2EFDEFGAEDC>AB<CD30CDE30FEEDC>BA30<C120>B120A<D30CDEFGAEDC>BA&A30]"
Before I posted a picture of this I accidently typed a second 1 after after the T for timing so instead of T121 it should be T12. sorry :( also this is only the third mml i have written, so I am new at this.
I hope I didn't come across as mean. I'm just enthusiastic because for me, a big part of having Smilebasic (and Petit Computer before it), is getting to write music. I hope some of what I wrote is helpful as you continue writing MML.