Low power widefields are nice if you live without light polution.
You'll know yourself from using the 25 and 30mm .
I would start with a
good barlow, such as the Orion 2x Ultrascopic 3 element. This will give you the following effective focal lengths.
30mm
25mm
15mm (barlowed 30) Good for dso's
12.5mm (barlowed 25) Good for dso's
4.5mm (barlowed 9mm) very high mag , rarely useful
4mm (throw it away
)
The beauty of a barlow is that you can view at higher powers and all with the comfortable eye relief of the longer focal length eyepieces you already have.
As for eyepieces, a 12.5mm when barlowed at 2x gives a very useful magnification with your scope for viewing the planets.
When buying eyepieces and the like , buy quality and cry only once