Please correct my Spanish sentences. Gracias.
La persona que se sentó al lado de mí a mi lado en el avión era tan gordo gorda que no podía moverme.
The person who sat next to me on the plane was so fat I could not move.
La persona sentada a mi lado en el avión era tan gordo gorda que no podía moverme.
The person seated next to me on the plane was so fat I couldn't move.
La persona que estaba sentando a mi lado en el avión era tan gordo gorda que no podia moverme.
The person who was sitting at my side on the plane was so fat I couldn't move.
Note: the prior sentence should not use sentándose, because sentirse only refers to the orginal act of sitting down, not the "continued sitting in one place" that the person performed.
La persona que estaba sentado sentada a mi lado en el avión era tan gordo gorda que no podía moverme.
The person who was seated at my side on the plane was so fat I couldn't move.
Espero que la person que se siente a mi lado en el avión no sea demasiado gordo gorda.
I hope that the person who sits next to me on the plane isn't too fat.
Please correct my Spanish if necessary. Of the first four sentences, which, if any would be the best way to say it? I personally like the first one because it emphasizes the person sitting (after I was already seated) next to me by using the preterite). The second one, to me, emphasizes the duration of the event although I think the remainder of the sentence does that well enough in the first sentence. The fourth sentence seems to just say the same thing as the second in a more complicated way. The third sentence, using the continuous form of the verb (non reflexive), doesn't seem very "Spanishy" 
Thoughts?
Also, am I correct in using the subjunctive twice in the last sentence? I think I should because, for the first verb (sentarse) the person who will sit next to me is unknown, and the second verb (ser) is the one that is being ruled by the Espero que clause. Right?
3 Answers
Persona is a female word so you must use gorda instead gordo.
The first one is wrong.
You can use two options to express this
A mí lado . A tu lado. a su........
Al lado mío. Al lado tuyo.....
Only "al lado de mi" if mi works as posessive
al lado de mi hija/perro/maleta. Al lado de tu hija/perro......
al lado de mis hijas/perros/maletas....tus....sus...
The second one is correct using gorda
The third and four are the same sentence and are correct using sentada and gorda. Remember persona female then sentada. Gorda. Hombre ( male) sentado gordo
The last one is correct using el avion and gorda.
If you want to emphazice the frustation of the event use que no me podia mover or stronger than this one. Que no podía ni moverme
The use of sudjuntive it' ok.
The last one is totaly usable and common but a joung person probably would use something like this.
Ojalá que no me toque un gordo/una gorda en el asiento de al lado.
This is from a prior post by Lazarus
To sit: to (cause someone to) be in a position in which the lower part of the body is resting on a seat or other type of support, with the upper part of the body vertical. Eg. to sit at a table/desk
The fundamental difference between this verb and the Spanish "sentar(se)" is that in English the verb can be regarded both as a change of position and an ongoing action (to continue to be in that position), whereas in Spanish "sentar(se)" is only the act of moving your body so that the lower part of it eventually rests on a surface. As soon as you touch the surface, the action of "sentarse" is over, like in the example breaking the object. Once the actions are over, the object is broken (you are not longer breaking anything) and the person is "sentada" (you are not longer "sentándote"). In English you are sitting, which means that it is an ongoing action, which consists simply on remaining in that position, whereas in Spanish your position is just the result of a completed action (sentarse) that lasts less than a second on average. Unless you move, the result of your finished action is to remain in that position (the broken object also remains in that state). In other words, after you "te sientas", you begin to be "sitting" there. Two different verbs. A sentence like "Estoy sentándome" (literally "I am sitting") does not mean that you just stay seated, but it describes a one-second action as your body moves a few inches towards the surface you'll rest on - it turns a very short action into a slow motion movie of it.
I would say either:
a) La persona que estaba sentada...
or
b) La persona que se sentó...
In both sentences I would say:
...que no podía moverme.
The last sentence is correct:
Espero que la persona que se siente a mi lado en el avión no sea demasiado gorda.
In the third sentence (The person who was sitting at my side on the plane...) you could also say:
La persona que venía sentada a mi lado...
