ok here's my 2 cents. given what you are cooking the choice for me would be:
chicken
oak 30% for heat and apple 70% for flavor (shame you don't have pecan cause that would be my 1st choice)
tuna;
since you don't have orange wood i would go with 100% apple.
but you could get around the no orange wood by marinading the tuna in a little orange juice and lime juice but for gosh sakes don't leave the tuna in for more than 30 mins or it will cook.
if you don't want to do that then you can take some oj concentrate and mix it with sour cream and a little cilantro and just for smell a seeded and deveined habanero pepper. mix that to sauce consistancy. you might like it.
BUT UNDER NO CIRCUMSTANCES WOULD I EVER USE MESQUITE!!!!! an i don't care what can of worms i open up there lol
jack