I so "ditto" what Gardengal said. The walk itself is the problem. Fortunately for you, the walk is small and would be relatively easy to redo completely. Even as a DIY project. (And raise it up a little.) You could redo it something like this ...

And the step needs enlarged. The existing one looks like step for RV.

A third vote for moving the walkway and widening the step. It really isn't a problem that can be solved by plants.

Yes I agree a larger walkway is needed and that is our plan in a few years when we do our driveway at the same time. But I am looking for a temporary solution until then. Even if I do plant annuals, would it look better to plant tall ones than shirt ones?

I'd try wax begonias, the ones with the burgundy foliage and white flowers to echo the colors in the main garden. They're used as bedding plants here in front of business signs and get really full and look good all summer.

I would keep it low & full ... like the wax begonias as suggested by mayflowers. And no other plants mixed in.

A new walk will be ideal. In the meantime, for some weight on that side, you could do a really full hanging basket. Or a vine might work in your narrow bed with a small obelisk in a pot or growing up the porch railing. Also looks like you have a pot around the corner by the garage--this could be bigger and have bigger plantings to add some presence.

If you're more ambitious, you could also cut a wider temporary bed on the lawn side bordering the walk. Essentially using the space that will someday be a wider walk. That would add weight, but would obscure the existing narrow walk somewhat. Still give you a bit of sense of walking "through" the garden to get to your porch. In that case, I'd use your narrow planting spot for some low growers like pretty sedums or groundcovers.

Your home is very nice and you have done a great job with the planting on the other side!