What site are you using to look these up? Do you have to go to each individual cruise line to get prices or is there a similar search engine to google flights that lets you see everything. The cheap 1k ones sound tempting just to get away for a week with good food.
We typically cruise with just Royal Caribbean (we're Diamond there now, so there's some perks that make loyalty kinda sorta worth it) but we've also sailed with Carnival just to see if it was as ****** as we'd always been told it was. Surprise, we liked it - some plusses vs RCI, some negatives, but all in all positive. A cruise is what you make of it honestly, and some people are never happy, and others like us just go with the flow and have fun no matter what.
Considering NCL as well, some of our crusing buddies have gone with them and liked it.
In our case, we just shop around on the cruise companies websites themselves. Once you narrow down the number of days and area you're looking for they have pretty solid search tools that really narrow down the options so you're not trying to find a needle in a haystack, figuratively.
We've often shop based on price as well and then work vacation around that. We did a 14 nighter for under $1000 (for both of us!) this way about 6 or 8 years back, it was insane, and did a Grand Suite on Carnival on a short notice booking (in the case of cruises, about 30-40 days out) about 4 or 5 years ago for $2500. Sometimes you just stumble across great deals, but we typically find they're out there either a year before a cruise sails, or at around the 30ish day point once final payments have been made by everyone else already booked and they're trying to pump full any remaining empty staterooms.
...but prices on cruises have spiked in the last 6-8 months as the ships are sailing at capacity again, so, yeah, we're not finding the deals there has been in years past, but still, compared to some all inclusives we're seeing, still a deal.
Stay away from the 3-5 nighters, they are often just booze-cruises, which if that's your thing I guess is fine, but it's not our bag.