You don't need opinions. They are only that, and can be losers. You need good advice, which will come from good sources. Go to your school, go to career counseling, and ask for any books which will tell you the different career fields that a Masters in Public Admin. will qualify you for.
Human resources is a good field, but again, look up how it can be used besides just in a company as a personnel person. If it is what you want to do, don't hesitate to pay a little more to get what you want. The money will come back in the job you get. Don't start penny pinching when you are so close to your career field.
Envoronmental policy..watch those online programs. My son took one, and never could get a job in that field. He is now working outside of the career he paid so much for. Do your homework on this area. EP is a good choice,, if you really have a passion for this type of thing.
Transportation..again online. Be careful.. Why would you now want to go on for more education, when you can use what you have, and later branch out.
Public Admin. is a great field, but it seems like you aren't sure how to use it. I had an AA in journalism, went on to do accounting, and then PR, got a degree in Communication, still doing PR work, which led to editor of newspaper (local), which led to PR in a Water Association. Continued with my education at night and got Masters in Counseling, with two more years of Alcohol/drug training. In all of this, I took classes when I could, and when I had the extra money. If you notice, everything centered around WORDS. Why. My passion is the English language and words. So find YOUR passion, and pursue that. Otherwise you will be miserable, and not like me, loving every minute of every working day.
WHAT IS YOUR PASSION? WHAT WOULD YOU DO IF NO ONE WAS PAYING YOU TO DO IT? Good luck..