LOR question: Professor vs a PhD work supervisor?

[MCS_aspirant]

I am in a really tough dilemma. So, do please help if you can.

I have exceptional academic record at a top 5 institute for Aerospace and have an unofficial offer with funding from the lab I work as an undergraduate. I currently work in two labs, serve as an academic advisor and a dual major (Aero E., and applied physics). I want to go to MIT/Caltech Aero program and hence I want to keep everything perfect.

Here is my situation:

Reco. 1: Research Scientist and my immediate supervisor for 2 years. Given me A+ in directed study courses (3 semesters, 3 A+'s). More like a friend. No doubt that she will be extremely positive.

Reco. 2: Professor of Aerospace, well known in his field. I took a PhD course with him when I was in my 3rd year and got an A. He said without me asking "I would have taken you. But I am not taking students next year". Told me he will hook me up with a professor in my present univ. (but I don't really want to stay at the same university). Taking another advanced course with him next semester.

Reco. 3: THIS IS THE REAL QUESTION!

Option 1: Academic Coordinator, has a PhD. I also work as a peer academic advisor and she has said she will be very positive and supportive (I 100% trust her). I have working under her for 1 year and she thinks I have the best performance of all the advisors. I do have some achievements in advising office like enhancing student turnout and increasing the number of academic events. This will bring VARIETY to my letters.

Option 2: Full professor in physics. Have been working for ~7 months (research) and meet him everyday. He is one of those guys who never expresses lots of emotion. He will always say "Good!", "Excellent", but would never say "You are the best" or never ask me about anything other than lab work. He will definitely be positive, but I am not sure how positive it will be. We are certainly publishing in 6-8 months (or even earlier) (alas! I hope it was before my grad application). He can mention about how close we are to getting results and that I am doing something very publishable. This will likely add WEIGHT to my LORs.

VARIETY vs WEIGHT? Could someone give me some suggestions? If any additional details will help you, please let me know. I really need some hints.

Edited August 3, 2011 by MCS_aspirant

[eklavya]

why not both? i've seen many people, some of whom were my own friends, sending 4 letters tho only 3 were required. one extra letter shouldn't hurt your chances. if anything, it will help.

[MCS_aspirant]

why not both? i've seen many people, some of whom were my own friends, sending 4 letters tho only 3 were required. one extra letter shouldn't hurt your chances. if anything, it will help.

The thing is- MIT Aero clearly says "Please submit only three letters of recommendation, using the electronic recommendation service that is part of our online application. Our online service will only allow for the submission of three letters, and our committee will not accept further paper recommendation letters."

Any further thoughts? I will certainly send 4 letters whichever universities possible.