I picked up a CZ 75 sp-01 tactical last night and was wondering if there are any "must have" mods? Its my first CZ pistol so any comments would be appreciated.

I think new wood grips are the first order of business.

First and best mod for me was aluminum thin grips.

Lots of stuff came after that, but the grips are the best bang for the buck.

I swapped out the grips, the sights, and the hammer & recoil springs.

Of those I would say the only necessary modifications for most people would be the grips and maybe the hammer spring. I shoot competition and use a 15lb mainspring with a 13lb recoil spring for 9MM minor loads. Although I have yet to try the harder Russian primers, the gun has worked well with Winchester and Federal primers.

In the end, whatever modifications you consider will depend on whatever your philosophy of use will be for the pistol. My SP-01 Tactical works as both my competition gun and main home defense gun.

My CZ came with tritium night sights. Did yours come with them too? Curious to know why you swapped them out.

Yes it did, and they were good sights - quite suitable for most situations. However I swapped them out for Cajun Gun Works competition sights for two reasons: I prefer a fiber front sight with a plain rear sight and I had the extra money to spend since I found my Tactical LNIB with a good discount.

The CGW spring kit and a lighter weight recoil spring would be a cheap and easy trigger improvement. CZ's are know for being oversprung from the factory. I'm running the 11.5 hammer and 11 lb recoil spring in my SP01 for IDPA, and wouldn't go that light on a defensive pistol. I've never had a light primer strike and only use factory 9mm ammo from PMC, Winchester, Federal and Blazer Brass. But, I am also running a CGW extended firing pin. Since you have a tactical I would also get a CGW slave pin to aid in future parts upgrades were you need to disassemble the seat cage. CGW offers a lot of options depending on how wild you want to go and the end use you have for the pistol. I went full blown competition oriented and have a 6 lb DA and under 3 lb SA trigger pulls that are 100% reliable.

spring kit from CGW

Spring kit and enhanced firing pin.

Grips, either thin aluminum of VZ. VZ makes a nice wooden grip that they are discontinuing

Not a fan of wood grips.  Looks great but for BBQ guns. The VZs are better but the stock rubber ones are the best.  I'd probably get an aftermarket hammer and the extended firing pin for now.

Mine is currently for IDPA/USPSA use only and has the following mods.

The first stage was as below:
Polished feed ramp, sear, trigger bar, breech face, race hammer, 13lb main spring, 15lb recoil spring, slide stop cut back, short reset disconnector and Dawson FO front and competition rear sights.  This was a vast improvement over stock for trigger pull and sight picture but it would not reliably light off factory ammo with the light main spring.  I ran it for a couple of matches and had at least 3 failures to ignite in each match.  (had zero prior to this work).  

Second Stage:
Extended firing pin, reduced firing pin spring, firing pin block removed, FPB lifter removed and replaced with CZC spacer.  
THIS is the cats azz.  The reset is much shorter, 100% reliable ignition and so buttery smooth.  I handled a Shadow after the fact and it was actually better than the Shadow finally.