Hello and welcome to CN.
People here rave about the 8 and 11 mm plossl for planetary eyepieces so you have chosen well.
Planets really test your scope, because they are viewed under high power and have fine, low contrast detail.
In general if you have an f/6 scope a good place to start looking at planets is with a 6mm eyepiece.
eyepiece_focal_length / f_ratio = exit_pupil. Which you can read about here. I like to view planets at about 1 mm exit pupil.
For your scope that is 200x.
If the night has good seeing I would think you could to to a 5mm.
Planetary viewing requires magnification to see small details, but also requires a bright image.
If you magnify too much fine detail is to dim to see.
You could get a 2x barlow for your 11 and have a 5.5, which is a nice mag.
I have several barlows gso and meade. I don't see them degrade the image. Many people here
rave about the televue barlow, so if you have deep pockets think about one of those.
As Shaula says, sometimes a zoom is the best eyepiece for planets. The reason being is that
seeing conditions can change in an instant. With the zoom, if seeing clears up you can zoom in
without fumbling for eyepieces.
Besides the eyepiece for best planetary viewing do the following
Read up on collimation. This is essential for high power viewing. You have to do a good job. Average is not acceptable.
Take your scope out well before you view. A warm mirror will lead to a boundry layer forming on the mirror (like a mirrage).
Also thermals rise up on the tube.
Do not view over house tops, roads etc. These soak up heat in the day and release it at night, making the air wavy.
A baseball or soccer field is ideal. If you live near the ocean it is good to view over that too.
In planetary viewing "Seeing" is everything. Think of looking into a swimming pool. Calm day you can see the bottom clearly. Lots of kids
jumping and splashing, you can't see into the pool. That is what seeing is. Stable, "smooth" air.
In my area the best days to view planets are the hot hazy days of summer. The moisture in the air makes it more stable.
Planets are not effected much by haze.
One other thing is to consider a wide field eyepiece. It might not be as sharp as your televue plossl, but you
will have to bump your scope less to track. It is a trade off.