Hi scalesandfins, this is my first post here and all the way from Australia!
Lace monitors are probably my fave available lizard here

I've worked with most of the monitor species that can be kept in Melbourne, Victoria but of all of them, I'd say that lace monitors have the biggest personalities. They do get large though; my male is over 1.8m (however much of that is tail) and a mate of mine has a big old boy that was considerably longer than 2.1m on last measurement. So on that note, I would like to stress that gaining some experience with other large varanids before purchasing lacies would make your experience much more enjoyable and much more safe. Being semi-arboreal, they are equipped with incredible claws that will do some real damage if they get a hold of you. Though Tony and David (from youtube) have exceptionally well behaved laceys, most keepers find that this species is very willing to bite (unlike others eg spencers montiors, gouldii, mangroves etc) when it feels provoked; so learning how to interact with/handle other large monitors before jumping into these lizards would be beneficial imo. And the feeding response on them is out of this world; certainly among the most likely times to be bitten is at feeding time!
Housing a large active species like these can be a challenge, especially if in a particularly cold climate. Your summer temps sound ok for outdoor accomodation; but how about winter temps? Here in Melbourne (southern Aus) we get winter lows of just above 0 degrees celsius; but they are among the most cold tolerant monitor species and I house my adult pair outdoors all year round in a large aviary (4m x 4m x 2m high). This is the southern most tip of their natural range; and I still provide a heated box within the aviary to take the chill off of them in winter. Any colder than this, and I would not keep them outdoors - not during the winter months anyway. They do need a reasonably tall enclosure; but whoever quoted 12' high is being excessive - the larger they get, the terrestrial they become, particularly big males so cluttering the enclosure with too many branches/logs etc may become a little pointless once they get past a certain age (i know, because it happened to me lol!).
As said, they can be tamed down into "relatively" trustworthy creatures, but it takes a heap of work and is easy to screw up. My female was handled in the "old school" method of taking them out most days from hatching, and handling regularly from day one...and although she is more or less handleable/tame, I dont believe this is the correct way to go about it these days...slow and steady is the key. They're incredibley smart, so teaching them that people mean no harm/aren't going to tear them out of the cage/scare the heck out of them is important...my Bells phase male doesn't trust humans due to being mishandled by his previous owner, and I doubt his attitude will ever change. Call it a grudge if you will!
If considering other monitor species (perhaps as a prelude to lacies?) then V. gouldii, or V. spenceri would be my 1st choice. Both are relatively uninclined to bite, are a little smaller (though some male spencers are MASSIVE bulky lizards haha) but behave in a similar manner to lace monitors. Most Mangroves are too skittish in my opinion; beautiful as they are. As for Asian/African varanids - I can't comment having not kept!
Hopefully that has helped your decision a little - they're superb pets but only if you're willing to dedicate the time, space and effort to them. I just had a clutch laid on the 30th by my two - now for the agonizing 9 month incubation period
All the best,
Trent.