I am considering painting the 30' tower to make it look better.  I would rather not throw tons of money at it.  Just cover the rust and give it a uniform look.

I have had decent luck with this;

https://gemplers.com/collections/rust-converters

Coat with enamel after the converter is cured.

Op just remember start at the top and work down...

Zinc-It
Cold galvanize spray.

I'd consider replacing it with a Rohn.  

Those ladder-style towers are rather flimsy - as wind twists and torques on the tower, those ladder "rungs" fatigue and welds break.  Those towers can go from "safe to climb and use" to "unsafe and dangerous" in a hurry.  Paint hides cracked welds and flaws.  

If the outside looks that bad, I'd be worried about what the inside of the legs looks like.  Rust and corrosion weakens the structure from the inside out too.

If you want to clean it up for aesthetics, i'd shoot it with cold galv.  I use ZRC cans.  
But again, I'd be real leery of doing anything on it without knowing a lot more about the complete condition of the tower.

Also, tower painting fucking sucks... hire that shit out.  That is a job I will not do.

The question is how much money are you willing to throw at it? Best way to paint that would be with a portable bucket trailer so there's a need to rent one (especially if you don't already have tower climbing gear). Some OSPHO or other directly paintable rust inhibitor and the paint. The other option...a new house bracket a base plate, and three sections of Rohn 25 plus bucket rental and you could have a new (hot dipped galvanized) tower for around $1000 that will last 40 years. Personal opinion, once you start seeing rust on the outside of the legs...there's typically going to be more on the inside.

This. And ground the new one.

An excellent example of why the original builder of that antenna should have put in a tilt-base.    

Lots of problems with putting tower bases directly into the concrete like that.  There is a whole thread on that issue over on the QRZ antenna/tower subforum on it.

So this tower was placed around 31 years ago by the original owner.  Structurally only thing I did was attach it to the house up top so the anemometer's wind direction would not be effected by swaying in gusty winds. I have a scanner antenna and the anemometer with its solar/wireless box that transmits down to the the rest of the Davis weather station down on the ground.

Only other addition I would like to add is a ADSB antenna and hardware box but I still need to research how well it will work only sending DC up the tower to power the hardware (Raspberry Pi and WiFi)

That is why I wanted to keep it low cost with just some protection and make it look nicer.  I have no doubt it would stand another 20 years if I did nothing. The legs meeting the concrete look fine and the tubing is sealed from water intrusion.