Thank you all for taking the time to pitch in! I greatly appreciate every single post, so, I´m going to try to sum up all the answers.
So yeah! This was my first paid gig, and I honestly did not charge enough. I was told to meet with them to give them an estimate, I only took the camera with the 20mm to take some test shots. Once I was there, I was asked to do the photo shoot that very day and they seemed happy with the results I showed them in the camera screen. I was also told these would be used for their online blog, so I charged for a simple photo shoot that wouldn't take me more than a few hours. It ended up being really intricate and they will use them for all of their corporate communication. So $300.00 USD simply won't cut it. I guess I made a lot of rookie mistakes there, but I rather have a good recommendation from my first customer and retake those two shots than to get all uppity with the money. All the interior shots came out really good anyway.
To sum everything up, renting equipment is a no go for the money I charged, and I really don't have time to set anything up since the shoot is tomorrow morning. But, I guess I can solve the situation with these posts:
The perspective in these is not working, I feel like I'm on the ground looking waaay up. If I'm using a shorter lens I usually use a 40-45 or 50mm. I'd say to move back but apparently you can't get back much further from the building.
You don't need to get the whole building. You need the viewers to see what's important or significant. Frame it so you get for the first one the doorway, the statue to the right and some of the brick wall, and the concrete sign above.
I'd do more than one photo of that - probably framed horizontally and maybe frame it so the top of the photo is just above the lettering. In another I'd probably try vertically to include the statues above the lettering (maybe include the steps, maybe not). You might be able to get something from slightly to one side but you don't need a lot of trees and bushes and you don't need part of a building chopped off to the left.
With the second one I'd try to get the doorway but not necessarily the windows above or to the left, you don't want them chopped off so I'd probably keep them out of the frame. This one benefitted from some cropping and adjusting but you definitely need to reshoot that first one. To me that isn't usable for a university website/catalog etc.
Move around and try different vantage points. Be aware of the reflections in the glass to get something reflected that looks good in the photos (seems to be trees behind you which could work nicely).
Awesome! I can maybe get an interesting perspective only showing parts of the building. Maybe take multiple shots. Thank you Vintagesnaps!
Scissor-lift is the best idea but, failing that get on top of a panel truck or a large A-frame ladder that will get you up off the ground a good ways.
Sometimes the solution to a problem is so obvious that you feel like an ass when you find it. An A frame ladder from the school's maintenance team would do just fine. Thank you The_Traveler!
An awesome skill I will work to acquire before my next assignment. Thank you Derrel!
Aside from this, I asked a friend to lend me his Sony NEX 5N with an 8mm Fisheye lens. I´m hoping I can fix the distortion in post and get some cool perspectives while getting everything in the frame.
I will post my work in the next few days comparing cropped shots with a 35mm, shots from a ladder and the corrected fish eye shots. Thank you all for your input!