What type of opportunities or options for commissioning does a 29 year old enlisted National Guard soldier have?

Since you are almost done with school, your option is OCS. The Guard has three versions they will let you follow, depending on the state. The Traditional National Guard OCS is 14/16 months that includes two annual training periods. There is an accelerated version that I know little about, other than the dropout rate is high. The last version is the 3 months long standard Army OCS. All have there good points and bad, depending on your situation. Don't let your age worry you, I commissioned two months before my 30th birthday. Any method you chose will require you to do an Active Duty Basic Officer Leadership Course for your chosen branch. How long depends on the branch, but plan on 20 weeks plus as a minimum. Being in the Guard does allow you more control over your Branch and you will generally know where you are headed before you commission. Be aware that it is still needs of the Service.
OCS is a bigger pain in the ass than BCT. It may be because I already had been through all the petty stuff when I enlisted, but I was my least favorite duty of everything I did in the Army and Army National Guard.

You could pursue an AMEDD Direct Commission as a 70D. CPT Enrique M. may have some tips there

Or you can ask for a direct commission. I would recommend that rout first.