Who is "Ashrei"?
Rashi: One whom You choose and draw him close, that he will dwell in Your Chatzeros.
Radak #1: (a) One that You draw him close. (b) One who will reach the time of the salvation, the generation that You will choose and raise it from Galus to bring it close to You, and dwell in Your Chatzeros.
Radak #2: One whom You draw him close to dwell in Your Chatzeros, above in Your Kodesh Heichal.
Malbim: It is one whom You choose and draw him close to help him against his Yetzer. It overpowers him every day and seeks to destroy him - "Tzofeh Rasha la'Tzadik u'Mevakesh Hamiso" (37:32). Without Hashem's help, the Tzadik could not prevail - "Hashem Lo Ya'azvenu v'Yado" (ibid., 33; Kidushin 30b). He will be able to dwell in Your Chatzeros, and never leave Beis Hashem.
With what good will he be satiated?
Rashi: The good in Your house, and from the Kedushah of Your Heichal, in which Your Shechinah dwells.
Radak: [The generation that returns from Galus] will be satiated with the honor that will dwell in the Kodesh place in Your Heichal, i.e. the Dvir (Kodesh ha'Kodoshim) in which the Aron is.
Malbim: (a) We request that You give rain in its time. (b) We should be satiated from "Kedosh Heichalecha" - to always engage in Your Avodah and become sanctified from its Kedushah. This concludes the Tefilah.
