Hi Sharon! Congrats on booking your flights
Most variants on la Plata are actually routes that join it from other starts than Sevilla. You can chose not to start from Sevilla if you want, but there are only 2 variant on this Way: after Salamanca, you can go either by the Camino Sanabres (which can also go 2 ways) or by the rest of la Plata to Astorga + the end of the
Camino Frances.
I joined la Plata in Merida from the Camino Mozarabe (started in Granada) and went to Santiago with the Camino Sanabres, which I loved. La Plata is not a popular route like the Frances, it's not as touristy. I could describe this Way as a gigantic Meseta
The Sanabres is even wilder, but I found it amazing.
Like you said, there is plenty to see along the way.
Like domigee said, most cities are enjoyable. Caceres has an beautiful historical city center; Galisteo is a very interesting city for its architecture; the albergue and the owner in Fuenterroble are very nice; Salamanca is a big city for cultural must-see.
On the Sanabres, Santa Marta de Croya has a nice place to stay at and one of the oldest statue of St James presented as a pilgrim; Villar de Farfon has a nice albergue (Rehobost); Lubian is a nice village with an interesting energy; the Rincon del peregrino in Albergueria after Laza has a nice albergue and its bar is not to be missed (scallops all over the place, pretty famous!); I didn't really like Ourense, but nice things to see there; Cea has a nice albergue. Then it's Santiago!
In between cities are also lots of nice places... Landscape is breathtaking most of the time, so I'm not going to list it, you'll see for yourself
The embalse de Alcantara (a bit after Caceres) is nice to stay at; the ruins of Caparra are impressive (its gate is the symbol of la Plata, the only problem is it's more or less in the middle of a 40km stage that can't be shortened without getting out of the path); there is an amazing point of view after Fuenterroble, at the top of the hill with windmills (I passed the wires to sit at their foot to admire the landscape: it's forbidden but worth it).
On the Sanabres, the dam and lake before Villar de Farfon is very nice and bathing friendly (although in April...?); the stage after Puebla de Sanabria is very nice (but tough on the first part); so is the one between A Gudina and Laza (means to stop in between, don't remember the name of the village); so is the one between Ourense and Cea (I loved it despite bad rain...).
Then it's Santiago!
I think Santiago is also a place that's worth it
Here the
wiki of la Plata + the Sanabres (in Spanish, but Google can translate it, can't he?)
Buen Camino