It seems like every general conference they announce two temples, one from the US and one outside the US. There is a great blog about lds growth that gives an updated map of potential temples. It is hard to understand the exact reason why a certain location is chosen for a temple but the following surely play a role: number of temple worthy members, number of stakes, distance from nearest temple, ability to purchase land, and rule of law in the country (meaning can the church build a temple without having to pay bribes and build a temple knowing that there won't be a civil war the next year). So with that said here are my top two picks with my first and second runner up.
US temple: Colorado Springs Colorado. The church seems to be investing in it's core in recent years. In terms of missionary allocation and temple building, the Rocky Mountain region has really seen a sharp rise in temples (especially Arizona, but the entire region). This is understandable, this is where the active tithe paying members are, this is where the missionaries come from. It is only logical that these members get the blessings of a temple, and logical that the church would invest a temple in these locations. The Fort Collins Colorado temple was just announced in April 2011, but on the other hand there has been growth in Colorado as well. Recently there was a new stake created in Aurora (Denver area) and most likely a 4th stake will be created in the Colorado Springs area if it hasn't already. According to the lds growth blogspot, one of their stakes has 14 wards and is ready to be split. This means that there is a large enough core in Colorado Springs to maintain a temple and a big enough core in Denver to keep the Denver temple busy once the Fort Collins and Colorado Springs temples are ready. Currently it is only a 1 hour drive from the Denver temple to Colorado Springs, but that is still significant enough to build the temple, especially taking into consideration the members living south of Colorado Springs in Pueblo. It also has a growing population, going from 214,000 people in 1980 to 426,000 people in 2011.
US runner up: Pittsburgh Pennsylvania and Jacksonville Florida. These are big cities that are far away from a temple (over 3 hours for both). They don't have as many stakes or members (Jacksonville is close), so that is why I am giving the green light to Colorado Springs. A dark horse candidate could be Tooele Utah. Tooele fits the mold of what the church has been doing recently, building in smaller towns where there are a lot of members that have to travel a small, but significant amount to the temple. The temple district is smaller (for Utah standards), usually less than 20 stakes and it is usually 30-45 min away from the nearest temple. We saw this in Brigham City, Payson, and Ceder City. Other locations such as Rexburg Idaho, Fort Collinns Colorado also fit this mold. If this tradition continues I would expect Tooele to be next. It is about 35 min or so from the Salt Lake City Temple and has 5 stakes in Tooele, with at least 4 more that would be in the temple district (from Grantsville and Stansbury Park). The population of Tooele is already over 30,000 (only 14,000 in 1990) and it will most likely continue to grow. One of the stakes has 12 wards, which means a sixth stake will soon be formed.
Outside the US: Managua Nicaragua This is the country with the most members that currently does not have a temple. I think the church has been hesitant to build a temple here because they have been building them in other Central American countries, and because Nicaragua isn't as pro West (also pro business) as some other countries. This could mean that it is harder to get land, building rights and so on. Ortega has been president since 2007 and has aligned Nicaragua against the US in international affairs, but with Chavez dead I see a slight thaw ahead which should make things easier for the church as well. Often the church can separate their relations from international politics, but not always (as is the case with Russia). If Nicaragua doesn't get it this time then surely soon.
Outside the US runner up: Puebla or Culiacan Mexico. There are tons of members in Mexico. Both of these locations would be a great spot for a temple. I am changing my dark horse candidate to Budapest Hungary! The church loves to build temples in Europe, even though there aren't very many members. They know that they can get permits easy and there won't be any problems. Unlike many Eastern European countries the church has done well in Hungary. There is a stake in Budapest, as well as two other districts. It is easy to get visas for American temple workers serving as senior missionary couples. The temple district would also include the Vienna stake and districts from Czech Republic, Slovenia, Croatia, Serbia, and Romania.
In about 5 years or so I think we will start to see a temple in some very exotic places such as Mongolia, Cape Verde, more African countries, Thailand, India, and other East Asian countries but I think they need a bit more time to develop. Within the last few years stakes have been organized in India, Thailand, Mongolia, Cape Verde, Russia, and Armenia. Once their leadership and members mature a bit more I think they will be ready for a temple, but I don't expect to see it this weekend.