This was extensively discussed
earlier in this forum when the idea of switching from one-way to two-ways came up. The reasons you bring up aren't necessarily as absolute as they sound - sometimes they would help, sometimes not. I mention some research on my posts there, but if you have anything else to back up what you're suggesting, please share.
(Incidentally, as you know Victoria is mostly one-way within the Downtown (Gov't St, Pandora St, Yates St, Fort St etc)

(Photo: me)
with two-ways at the periphery (Wharf St, Quadra St, Blanshard St etc). As are most Downtowns in Canada - a mix.)
By small alleys you mean like Fan Tan Alley? I get my haircuts at the Chinese barber shop in there - great place to watch the passing parades:

(Photos: me)
Might be hard to replicate that as many businesses would demand front parking access... or even if they didn't, developers would just build that way anyway (eg Broad St Crossing). Are there any buildings in Regina with an alley that could do this?
Yes, definitely more paths - in and of themselves they become attractions no matter where they lead. Eg Victoria Galloping Goose Trail (my
commute to/from work):

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Rooftop patios could work too - would go along nicely with green roofs, eg Victoria Douglas St:

(Photo: me)
Even if not patios, just having restaurants setting up tables right on the sidewalk would do - no need for separated patios. Eg Victoria Chinatown:

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That Tim Hortons in Broad St Crossing could've been set up like this, for example. Just a bylaw saying "No surface parking Downtown" and "Build to the corner" would've done it.
And simple things like banners: simple, because it's the colour and motion of the banners that makes the ambience, not what the banners actually say. Eg, instead of those "shop/dine/etc Downtown", just plaster the streets with colour and patterns that will
mean Downtown, rather than just state obvious advertising messages. Like

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Similarly, large green fluttering victorious banners would've been more appropriate for Albert St than small motionless "The Green Mile" signs in a dull staid serif font.
And instead of back alley graffiti, poetry:

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And instead of cracked concrete, paving stones and art:

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And on transformer boxes and storage containers, more art:

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One thing Victoria does too is
design guidelines. (Anyone who has read my posts before I'm sure saw this coming.) More than just guidelines for the city in general, there are even specific rules for almost every neighbourhood in town ("Designated Development Permit Areas"). It's a way to ensure subdivisions do not become generic cookie cutter copies of one another. (Maybe having a
Mayor who is an architect is helpful too.)
I really like this one though:
That's right, the
entire City for increased density, and rules about density that prevail over all other guidelines... and rules about heritage preservation that prevail over that. Not to say that modern buildings can't go up, eg smack in the middle of the remaining original industrial inner harbour boat yard:
Even in new construction suburbs (the Victoria-area version of South Albert St) you see the density at work:

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The point: I can't help but keep asking the rhetorical question - why does Regina not have design guidelines? The outcomes are so much better when you have them - and it's not like the City doesn't know they could do this. Just a matter of Googling around and seeing what the rest of the country's cities are doing.