I am just chilling out in the Ag Centre, killing rats, bunnies, opossums and desert lizards and occasionaly leveling up. I am really enjoying it.

I never played Wasteland when I was small, but I did play A LOT of the gold box AD&D games and loved to grind to level up (that forrest area in curse of the azure bonds or random hill giants in secret of the silver blades, anyone) and be super powerful later on in the game. It's bringing back old memories for me.

I'm not sure how long I will be able to grind to kill critters before I become completely bored. Is there another good place to grind for exp after I am finished killing cuddly little aminals in the ag centre?

Well... I'm playing for the first time, too. I mean I tried to play several times, but these attempts weren't successful :) During these attempts I've got some random encounters in the desert, so I think wandering around the desert is good thing to level up. If you ever played Fallout you can remember alike encounters, I think they came straight from Wasteland.

Best early-ish place I've found so far is the mine south of Quartz. You get jumped every 1-2 steps, and there are single-shadowclaw encounters (inspiration for Fallout's deathclaws?) that give 400 XP. You can also set up a macro to mine infinite money from a silver vein here if you have metallurgy and a pickaxe.

I would recommend finding some automatic weapons before coming here, though, as killing shadowclaws is difficult unless you have 1+ party member(s) Auto firing, or multiple party members Burst firing.

There are also some good places to get your individual skills up. Running along the windows on the roof above Ugly's hideout in Quartz increases Perception, while running repeatedly into the sand in the southern area of Needles increases Climbing. You can also increase Gambling via the slot machine in the Rail Nomads' camp, but like all gambling I've seen so far it's a significant money drain.