for all the spanish speakers out there

My future Hubby is coming to Buenos aires at the end of June so that we can make the official announcement of our engagement together, and we are organizing an engament party. We want to have a nice party here for all the people that, reasonably, won't be able to attend the actual wedding in the U.S.
This is what I wrote for the invitations:
(both our names at the top)
Con motivo de nuestro proximo casamiento en los U.S., queremos compartir con ud.(s) la alegria de nuestro compromiso. Los esperamos el sabado 30 de junio a las 20:00 hs
We want to share with you the happiness of our engagement. You are cordially invited to attend the celebration saturday june 30th, 20:00 hs
(then underneath, the address) Buenos Aires, 2007

and then for the personal invitation (the smaller card)

Participamos a ud(s) de nuestro casamiento
octubre 2007
City Hall, Austin, Texas

(we don't have reservations for october, but it is our tentative date)

*Any suggestions/ corrections?
*I can't find the equivalent word for "participamos", is there one?

Thanks in advance!!

I am not the expert here, so take this as you will. Participamos would be translated participate... but clearly that sounds weird. So why not.. we would like you to partake (or be part) of our wedding celebration? Or just change it all together... please attend our wedding celebration/ we would like you to attend or are inviting you to our marriage ceremony. Something to that effect maybe. Not sure that helps, but maybe some new ideas. Best of luck with that and the rest of your journey!!!

Aquí usan mucho algo que llaman ‘Save the Date’, son tarjeticas o recuerditos (portarretratos, detallitos con almendritas y esas cosas) que dicen algo así un recordatorio de que tu boda será celebrada en tal fecha.

En cuanto al wording, te recomiendo que hagas un search de ‘engagement announcement cards’ y allí encontraras miles de sitios que hacen tarjetas de invitación donde puedes obtener ideas para tus tarjetas.

Buena suerte y felicitaciones!!

Participamos - Anunciamos, compartimos

Therefore, you can say "We announce our future wedding on.... " - "Le anuncimos/participamos nuestro futuro matrimonio en... :

Hope that's helpful & Congrats on your future wedding!!!

Mil Gracias a todos!!!
I am out of my mind with joy that I've found such an amazing guy that loves me like he does, and the thought of us becoming a family is the greatest thing that's ever happened to me!

"Announce" looks like an excellent idea, I think I'll go with that, Thanks!

Rebex, You had the interview on friday and you got approved??
FELICITACIONES!!!

And good luck to you Paulino, looks like this process is not being easy for you, hope that things soon turn around for the best!

Thanks for the congratulatory wishes. He is picking up the visa today, so hopefully not much longer. Best luck to you all!!!