A track saw is a great option for long straight cuts. As with any tool you can find inexpensive to very expensive options. The cheapest option is to use a straight edge with a normal handheld circular saw. Next up are jigs that attach to a circular saw. Finally there are the true track saws. For the budget friendly end, look at the options from Kreg, on the high end, Festool.

A tracksaw will generally perform better than 99% of the tablesaws out there for breaking down sheet goods. And will be far safer as well (kickback is a bitch).

I clamp both ends of straightedge to the work, and use that to guide a handheld circular saw's edge.

If you're interested in making furniture you should check out Lost Art Press' Anarchist's Design Book. It describes making "vernacular" furniture, i.e., not fancy but sturdy and durable furniture.