One of the greatest places to go for some great insight into temples is D&C 109. This is the dedicatory prayer of the Kirtland Temple, the first temple to be dedicated in the latter-days. Joseph Smith gives some great insight into some of the blessings that come from attendance at the temple. There are three main categories that the blessings fall under: grace, knowledge, and protection.
Grace (BD defined as “divine means of help or strength.”)
Verses 10-13. Grace, assist us, glory of the Lord upon the people, feel the power of the Lord, secure a fulfillment of the promises. One of important points here is that we secure the fulfillment of promises. One of those great promises is help when we need it. Other promises, D&C 84:38, 3 Nephi 27:20, 2 Nephi 32:5.
Verses 14-15. At all times people go to the temple to learn to be more like God. Moses went to the mount (BD: mountains often serve as temples) and came closer to God. D&C 84:23, He then spent his time trying to get his people to have the same experience, so he was commanded to build a temple. 1 Nephi 17:3. D&C 121:33 “The Lord will not reveal anything to Joseph that he will not reveal to the Twelve or to the least and last member of the Church as soon as he is able to bear it.” (Joseph Smith, History of the Church, 3:380)
Verses 22, 24-28, 38, 46.
God does know what is coming (D&C 1:17) and will give us strength in time of need. 2 Kings 6:13-18, D&C 84:88 Matt 4:11 D&C 87:8 (This verse is shared after a whole section of war and coming destruction.) An example that the early Saints understood the protection the temple would give and wanted it, “On 3 February the Brethren planned to spot the ordinance work, and Brigham Young left the temple to make final preparation to leave the next day for the West. But seeing a large croud gathered to receive their endowments, he compassionately returned to serve them. This delayed his departure for another two weeks. According to temple records, 5615 Saints were endowed before going west.” (Church History in the Fullness of Times, p. 304)