For best viewing of the planets you want clear stable dark skies. The more stable the skies the more magnification you can use. However, all telescopes are limited to a maximum useful magnification. As a general rule of thumb that is approximately 2x per inch of aperture. This is not to say of the condition are excellent that you cannot exceed that amount, you can. But those nights are quite rare. That telescope being a 114mm will allow you to effectively use 228x magnification on a good night. Planets are often best viewed at magnification above 200x which is possible with that telescope. But, the size of the telescope is also limited in it light gathering ability and how good it can resolve small detail. Larger aperture equals more light grasp and a higher resolving power.
Another thing to take into account when observing the planets is the type of telescope you are using. The Nexstar 114 GT being a smaller Newtonian Reflector also has the central obstruction of the secondary mirror which will reduce the contrast of the image. When compared to a Refractor of the same size or even slightly smaller, the refractor would have a sharper image at the equivalent magnification. The only way to overcome this with a Newtonian is to get a large one. As already mentioned in the previous reply, to get more bang for your buck a Dobsonian mounted Reflector(Dob) is a good choice. If you want something you can effectively use 250x 300x or maybe more magnification without to much contrast loss as you increase magnification then I suggest at least a 8" Dob.
With that said, many people are under the misconception that you can magnify the planet considerably larger, and even possibly see it like you see it in pictures of it. That's not going to happen! Even in a larger telescope using 350x Magnification it's not going to be too much larger than what you may have already seen with the 114 GT. Maybe a little larger than a pea or about the size of the very tip of you pinky finger. But if you have the light grasp and resolving power you would be amazed at what you can see on the planet. You can see the swirling festoons among the bands and you can easily see the shadows of the moons as they pass in front of the planet.