You can park it with the strollers. Always take the key with you. If you are going to do this, remember these things:
A CM may move your
ECV, even if it is an off-site rental or personal ECV. They have seen pretty much every model and know where the free-wheel lever is. They may move it to a more convenient spot as they adjust stroller parking for crowds, parades, etc. Also, stroller parking is not always near the actual entrance of the attraction.
The exit of a ride is not necessarily in the same area as the entrance. You may have to walk a long way to get back to the ECV.
You may get stuck in a line for quite a while if the ride breaks or the posted wait time is not the same as the actual wait time.
If you do not have your ECV with you, you cannot use the accessible entrance to a ride (i.e. the one that avoids any stairs), unless you have another visual cue or a GAC. I see this all the time in DL (where much less is accessible than WDW) - people park the ECV, walk around Fantasyland, and then want to use accessible entrances with no way for the CMs to know they need it. Make sure if you need accessible entrances/exits (there are stairs in a few places), that you have some cue (cane, cast, GAC, etc) for the CMs to follow.
I suggest you take the ECV into as many attractions as you can, and save the walking for when you have no choice - for example, having an ECV can be a pain for attractions such as Haunted Mansion, so that may be one you want to walk. Especially keep it for shows that have hard metal benches with no backs!
When I first used a WC in WDW, I thought I would walk a lot more than I did - it was very surprising how much I kept it with me.
Always your choice, of course, but sometimes it may be easier for you to keep it than to park it.