Cinque Terre village for four nights?

You can easily visit all five villages no matter which one you decide to stay in. There is a train that connects them all in addition to the various hiking trails.

Here's what Rick Steves says about them (https://www.ricksteves.com/europe/italy/cinque-terre)

▲▲▲ Vernazza The region's gem — the most touristy and dramatic — crowned with a ruined castle above and a lively waterfront cradling a natural harbor below.

▲▲ Monterosso al Mare Resorty, flat, and spread out, with a charming old town, a modern new town, and the Cinque Terre's best beaches, swimming, and nightlife. It has the most restaurants, and the most comfortable hotels.

▲▲ Manarola Mellow, hiking-focused waterfront village wrapped in vineyards and dotted with a picturesque mix of shops and cliff-climbing houses.

▲ Riomaggiore The most workaday of the five villages, with nightlife, too.

▲ Corniglia Quiet hilltop village known for its cooler temperatures (it's the only one without a harbor), fewer tourists, and tradition of fine wines.

Pick whichever one strikes your fancy.

I would watch some videos of each of the villages and see which appeals to you. Also take into consideration the logistics of each town, knowing you’ll be transporting your luggage. We stayed in Manarola many years ago and it was quite a walk uphill to our lodging.

We stayed two nights and were able to visit each of the villages with no problem.

All of the towns are nice. For some reason, Monterosso is my least favorite, maybe because it's the largest. Vernazza is lovely and charming, but it tends to be the most crowded with American tourists, in part because it's Rick Steves's favorite town. Corniglia is the least convenient because it's so far above the train station - you either hike up a bunch of steps to get to the town or take a shuttle bus. The upside is, this makes it less crowded than the other towns especially after the day trippers leave. Riomaggiore is really nice too in my opinion even if a little less charming than Vernazza. Manarola is the smallest.

It's probably not a mistake to stay in any of the five towns.

I've been to the Cinque Terre a number of times and stayed in Levanto every time. Levanto is the town just to the north of Monterosso and included in the train pass that covers the Cinque Terre. While it's clearly not in the same league as the five villages (and nothing to look at from the water), it's still a really nice, pleasant town, just more "conventional." It's a little cheaper to stay there especially in busy times, and you are less likely to have to navigate a hundred steps up or down to your lodging's front door. Train connections to all of the towns are excellent, and you can even hike a few hours from Levanto back to Monterosso (not quite as nice as the hikes between villages, but also much less crowded, and you get a breathtaking view of all five towns from the point above Monterosso heading north).

https://cruisedig.com/ports/la-spezia-italy/arrivals. https://tinyurl.com/naz25ukk

When big ships are in port, Monterosso and Vernazza are the worst.See trip reports:

Manarola:

https://tinyurl.com/bdh572y7

https://tinyurl.com/2s4yazzy

Riomaggiore:

https://tinyurl.com/3ju7vy47

https://tinyurl.com/2r345mr7

This is really subjective. Do a lot of research on each village. Know exactly what experience you are looking for. Keep in mind that during season that the trains between villages are heavily crowded and the platforms can become a bit of a mosh pit. Consider ferry access as well.

Have fun!