If you're looking for a meeting place or a good stop around ½ or halfway between Eureka and Meridian, CA, you can try Laytonville, CA, which is about 2 hours southeast of Eureka, or about 2½ hours northwest of Meridian, CA.
Other possible places to stop near the midpoint include Indian Springs, Longvale, Tatu, Rowes, Farley, Burbeck, Crowley, and Sylvandale.
About ¼ or a fourth of the way, you can stop at Weott, CA. This is almost an hour south of Eureka.
About ⅓ or a third of the way, you can stop at Reynolds, CA. This is about 1½ hours south of Eureka.
About ⅔ or two thirds of the way, you can stop at Vann, CA. This is about 3 hours southeast of Eureka, or about 1½ hours west of Meridian, CA.
About ¾ or three fourths of the way, you can stop at Clearlake, CA. This is a little over 3 hours southeast of Eureka, or a little over 1 hour west of Meridian, CA.
If you drive straight through without stopping at all, the total distance is 247 miles. The distances shown above don't include local roads to get into each town, so if you're planning a long road trip, make sure you factor in traffic and road conditions, rest stop breaks, and interesting detours along the way. If you're in a rush, you can do the trip with zero stops, and your total travel time would be around 4 hours, 28 minutes.