If I have the seat/scooter throughout the day, I can usually make it all the way back to my room without problems. My issues tend to flare up after a long day of walking/standing. I have to admit while I don't mind using the ECV in the parks, I am petrified on driving the unit onto a bus, given that I don't use one at home, and am not proficient at maneuvering.
Remember that you can - like
@TCRAIG said - walk the scooter up and down the bus ramps. (and if you do, you may want to consider walking backwards down the ramp when it is time to get off the bus - with both hands on the tiller of the ECV so that you can "steer". And don't turn the wheels until you are certain that the back wheels are completely off of the ramp)
But, I promise that you can (easier than you think) get used to boarding and disembarking while seated on the ECV. Disney bus drivers are *experts* in getting you, on a scooter, safely on and off their bus. They do it all day, every day, and their number one goal is *always* your safety!
Always let your driver know that you are a new scooter driver - and it's ok to admit that you are nervous or worried
Drivers are not supposed to help you get the ECV on or off the bus (other than verbal instructions), so any "extra" help you get should always be counted as Pixie Dust.
When you board, remember that at the Resorts, there is a white painted rectangle with the handicap symbol on the ground; usually, the drivers try to stop the bus with the back doors at/near that rectangle. You can park inside the rectangle (if no one else is) to indicate that you are ready to board the bus. At most Resorts, one stop handles buses to several destinations, so if the bus approaching you is NOT going to your destination, try to make eye contact with the driver, and shake your head "no" to let them know *you* aren't waiting for them. They may still ask you directly, that's ok. When your bus arrives, give the driver a "thumbs up" or a big smile and a nod to let them know you are ready to go!
If you can line up straight on the ramp going up into the bus, it makes it a lot easier - go as slowly as you can, for safety! - and the driver will tell you when you reach the top of the ramp when to turn to the right. If another mobility device is already on board, and will be staying on board, you may have to drive further forward into the bus. The driver will give you instructions on how to (basically) parallel park the scooter - just stay calm, and follow them
Some drivers will, at this point, tell you to go ahead and take your seat, and they will tug the scooter into it's final position and then tie it down. (again, this is considered Pixie Dust)
When you get to your destination, the driver will open all the doors, and everyone will get off. Once everyone has gotten off the bus, the driver will close all the doors, walk to the back, "kneel" the bus, open the back doors, flip out the ramp, and then they will remove the tie downs, and it's time to turn the front wheel(s) of the ECV hard to the right, so that it makes almost a u-turn, and can line up to go down the ramp. Again, some drivers may Pixie Dust you a little and help with this - but if they don't, it's OK. Just try to be lined up as straight as possible to go slowly down the ramp. Make sure that your back wheels are completely clear of the ramp before you try to turn your front wheel(s) - otherwise, it can tip you over.
I can write descriptions of the process all day long, but until you do it yourself, it's hard to see that it can ever be easy!
If you decide to rent off-site and have the unit delivered to the Resort, try to make your first bus ride after rope drop, or take a ride to a less busy destination (like Disney Springs or a water park). That way, there is less pressure until you have had a chance to practice a bit! And before you even try to board a bus, take 10 to 15 minutes at the Resort to get used to how the rental handles - and boost your chances at success with the bus by practicing on curb cuts or ramps and parallel parking. Just practicing how fast, but more importantly, how slow your rental scooter can go can be really helpful, and make you feel more confident!
You can do it - there are thousands of folks who do this every week at WDW!
