My question: How would you pros notate this without messy ties and unnecessary rests for the various voices? Arpeggeios with sustained notes are very idiomatic to piano.
Thank you.
Absolutely just as 8th, 8th, dotted-half. Every pianist will know what to do with that. If you want, you can write “pedal ad lib” somewhere. Or a pedal line.
From one I’m working on at the moment. This is all that’s needed:
Dorico will let you slur whatever you want. You just have to cmd/ctrl click the first and last notes before adding the slurs.
Actually, the precise durations as you notated them would be unplayable for most pianists (you’d need to hold E and G# while releasing B, meaning you’d have to cover a tenth within one hand. And if you put pedal, the B will remain during the whole bar, i.e. longer than notated.)
As you mentioned, these are very idiomatic patterns that are best written as simply as possible, perhaps with a unprecise pedal indication as @dan_kreider suggests — though even that isn’t really necessary, as it’s implied by the context
You could also notate it like this, but that’s not what I would do, as it is unnecessarily complicated:
Thanks, everyone, for all the great comments.
First of all, I made a mistake. I meant for all the left-hand notes to sustain until the end of the bar, like this:
Oddly, however, when I slur the three notes in the left hand, I get this, which I don’t understand:
This seems overly complicated for a simple passage. 
It is interesting that, although I am a pianist, I find piano music more difficult to notate than orchestration, I suppose because of all the voices. Things are also complicated because I want the audio export from the score to sound good, so just writing con pedale doesn’t work.
If it is just a playback question, you can extend the sound in the Key Editor. Here, both notations give the same sounding result:
But also, normally, the pedal indications are taken in account for the playback, I think?
You can input precise Pedal indications and hide them.
As for the slur, select just the E and the G# and press S (and then F if necessary).
I really agree!
I don’t believe there’s a way to get slurs to cross voices, so when you shift-click that bar and add a slur each note slurs into the next note in that voice rather than the next note in that bar.
And yeah, I totally agree with notating piano music being more difficult than small or even large ensembles.
Welcome to the forum.
You can easily slur across voices by ctrl-click selecting the start and end notes for the slur and hitting S.
My apologies! I’m still kind of new to Dorico 
@ryanpetriello , Actually, I could not make @Janus’s suggestion work, so no apologies needed.
FEATURE REQUEST: It would be nice to have a function similar to the Chord Input function that allowed sustained arpeggios on a single voice. This would make entry of piano music much easier.
I’ve been reading fast the whole thread, and nobody uses l-v ties in those situations?
Actually, it’s very rarely used in piano parts—maybe because we use the pedal so much that l.v. is always implied!
Interesting. I’ve written laissez vibrer for harp once, but, generally for harp, cymbal, timpani, etc. I just write the note duration desired and trust the player to end when the note ends.
In this case, it’s more of a software playback issue.
I wouldn’t say it’s an issue, because if there were a tool that made Dorico play your left-hand notes tenuto, the right-hand melody would sound oddly dry, I am afraid.
The tool for global resonance is indeed the pedal — I think it’s the best way to get relevant playback in your case. If you don’t want to show pedal marks in every bar (and I agree you shouldn’t!), you can hide them — there’s a trick for that*. And pedal marks are easy to alt-click.
I assume the playback here is close to what you are looking for? (The con ped. is just a text, the real ped. marks are hidden).
Hidden pedal.dorico (1,3 Mo)
*Select them and set the properties like this:
Yes, I know the pedal is the usual tool… But I remember Debussy and Ravel using kinds of lv ties (actually, broken ties that don’t add clutter, and that are not implemented yet, but that can easily be faked now, with hidden notes)
