Is there a difference between sana and senin için?

Sana benden başkası yasak.  (To you, someone other than me, is forbidden)
Senin için benden başkası yasak. (For you... )

One more question:

Seni tanımak çok memnun oldum. (I was pleased to meet you)

Seni tanımayı çok memnun oldum. (I was pleased meeting you)

Not sure whether the infinitive becomes the object of the main verb (olmak) or not. :/

http://www.turkishclass.com/turkish_lesson_306 (için)

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"memnun olmak" is well nigh always used with the dative case (-e/-a)

tanımak (to meet (to get information about smb./smth. as first time))

tanı+ş(reciprocal)+mak------->tanışmak (to meet each other)

tanış+dık+mız(possessive)+a(dative)------->tanıştığımıza

Tanıştığımıza memnun oldum. (Nice to meet you (direct: I felt glad to meeting each of us.))

memnun (1satisfied, 2glad)

Bana hediye aldığına çok memnun oldum. (Nice to get a gift of you. (direct: I felt so glad because you bought a gift to me.))

hediye (gift)

almak (1to take, 2to receive, 3to buy)

Onları ziyaret ettiğimize memnun oldular. (They felt so glad because we visited them.)

ziyaret (visiting), ziyaret etmek (to visit (direct: to make a visiting))

Kendisini översek buna memnun olacaktır. (If we praise him, he will probably be glad of this.)

övmek (to praise)

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"sana" hinges on the dative case. "bana" and "sana" are the exceptional conjugations of dative case for the personal pronouns.