That's debatable as to whether you can hold TBT for the long run or use it as a "swing/day trading vehicle."
If we throw our personal market and economic opinions to the side then the rational conclusion would be to use it as a day/swing trading vehicle. TBT is a double beta etf which decays over time. If the treasury market trades sideways in a given range then the etf would trend toward zero over a given period.
However, if you take into account your own opinions such as "i believe the 20y treasury yield will rise to 4.5% by Jan 2011" then you'll probably would want to be in TBT since the etf will greatly outperform any single beta etf durinig that time. The decay pose a huge risk to your position.
The best way to take advantage of the decay is to short a double beta etf that is opposite the etf you would like to buy.
For example, UBT is an inverse of TBT. This etf is thinly traded compared to TBT. I thought about buying puts on the etf but the spreads were too large because of the lack of volume. With this trade, i would be using the decay in my favor.