The largest American Presbyterian denomination is the PCUSA, which is a typical “mainline” denomination. That is to say, the leadership tends to be quite liberal, but the rank and file range over a wide spectrum. None of them are ultra-conservative (those who oppose women’s ordination, for instance, have almost all left)–they range from moderate evangelicals to extreme liberals. As with most of the mainline denominations, some of the largest and most thriving churches are evangelical, and this no doubt has some impact on the denomination as a whole, even though the denominational bureaucracy tends to be hostile.
There are a lot of conservative Presbyterian denominations. The largest is the PCA, which split from the Southern Presbyterians just before the reunion with the more liberal Northern denomination. They don’t ordain women and are much more explicitly Calvinist than PCUSA. However, in my experience some of them at least have a fairly high theology of the sacraments, and while they’re mostly anti-Catholic there’s a movement among some of them toward a greater appreciation for the medieval tradition. The Orthodox Presbyterian Church is even more conservative, and the Bible Presbyterian Church is extremely fundamentalist. The Evangelical Presbyterian Church is more moderate–basically it’s identical in belief with the more conservative wing of PCUSA. They ordain women, for instance.
The Cumberland Presbyterians are quite different–they dropped most aspects of Calvinism in the 19th century, though I think they do believe in eternal security (like the Baptists). My understanding is that they’re not very conservative, but I don’t know much about them.
Of course, all of this assumes that you live in the U.S.!
Edwin